Fix CRUD documentation. (#7302) (#7303)

* Switch CRUD examples to included test code

* Remove examples folder

* Fixes

* Tweak tags

* Tweak formatting

* More formatting

* Finalise

Co-authored-by: Steve Gordon <sgordon@hotmail.co.uk>

Author: github-actions[bot]

docs/client-concepts/serialization/custom-serialization.asciidoc

@@ -63,12 +63,9 @@ We want to serialize our source document using Pascal Casing for the JSON proper
 [source,csharp]
 ----
 include::{doc-tests-src}/ClientConcepts/Serialization/CustomSerializationTests.cs[tag=usings]
-private async Task SerializeWithCustomOptionsAsync()
-{
 include::{doc-tests-src}/ClientConcepts/Serialization/CustomSerializationTests.cs[tag=custom-options-local-function]
 include::{doc-tests-src}/ClientConcepts/Serialization/CustomSerializationTests.cs[tag=create-client]
 include::{doc-tests-src}/ClientConcepts/Serialization/CustomSerializationTests.cs[tag=index-person]
-}
 ----
 <1> A local function can be defined, accepting a `JsonSerializerOptions` parameter. Here, we set `PropertyNamingPolicy` to `null`. This returns to the default behavior for `System.Text.Json`, which uses Pascal Case.
 <2> When creating the `ElasticsearchClientSettings`, we supply a `SourceSerializerFactory` using a lambda. The factory function creates a new instance of `DefaultSourceSerializer`, passing in the `settings` and our `ConfigureOptions` local function. We have now configured the settings with a custom instance of the source serializer.

docs/usage/examples.asciidoc

@@ -1,5 +1,5 @@
 [[examples]]
-=== CRUD usage examples
+== CRUD usage examples
 
 This page helps you to understand how to perform various basic {es} CRUD 
 (create, read, update, delete) operations using the .NET client. It demonstrates 
@@ -13,11 +13,7 @@ your C# file.
 
 [source,csharp]
 ----
-using System;
-using Elastic.Clients.Elasticsearch;
-using Elastic.Clients.Elasticsearch.QueryDsl;
-
-var client = new ElasticsearchClient(); <1>
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tags=using-directives;create-client]
 ----
 <1> The default constructor, assumes an unsecured {es} server is running and 
 exposed on 'http://localhost:9200'. See <<connecting, connecting>> for examples 
@@ -30,13 +26,7 @@ that map to the document structure being stored in {es}.
 
 [source,csharp]
 ----
-public class Tweet
-{
-    public int Id { get; set; } <1>
-    public string User { get; set; }
-    public DateTime PostDate { get; set; }
-    public string Message { get; set; }
-}
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=tweet-class]
 ----
 <1> By default, the .NET client will try to find a property called `Id` on the 
 class. When such a property is present it will index the document into {es} 
@@ -45,29 +35,15 @@ using the ID specified by the value of this property.
 
 [discrete]
 [[indexing-net]]
-==== Indexing a document
+=== Indexing a document
 
 Documents can be indexed by creating an instance representing a tweet and 
 indexing it via the client. In these examples, we will work with an index named 
 'my-tweet-index'.
 
 [source,csharp]
 ----
-var tweet = new Tweet <1>
-{
-    Id = 1,
-    User = "stevejgordon",
-    PostDate = new DateTime(2009, 11, 15),
-    Message = "Trying out the client, so far so good?"
-};
-
-var response = await client.IndexAsync(tweet, request => request.Index("my-tweet-index")); <2>
-
-if (response.IsValid) <3>
-{
-     Console.WriteLine($"Index document with ID {response.Id} succeeded."); <4>
-}
-
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=create-tweet]
 ----
 <1> Create an instance of the `Tweet` class with relevant properties set.
 <2> Prefer the async APIs, which require awaiting the response.
@@ -77,12 +53,11 @@ operation succeeded.
 
 [discrete]
 [[getting-net]]
-==== Getting a document
+=== Getting a document
 
 [source,csharp]
 ----
-var response = await client.GetAsync<Tweet>(1, idx => idx.Index("my-tweet-index")); <1>
-var tweet = response.Source; <2>
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=get-tweet]
 ----
 <1> The `GetResponse` is mapped 1-to-1 with the Elasticsearch JSON response.
 <2> The original document is deserialized as an instance of the Tweet class, 
@@ -91,25 +66,13 @@ accessible on the response via the `Source` property.
 
 [discrete]
 [[searching-net]]
-==== Searching for documents
+=== Searching for documents
 
 The client exposes a fluent interface and a powerful query DSL for searching.
 
 [source,csharp]
 ----
-var response = await client.SearchAsync<Tweet>(s => s <1>
-    .Index("my-tweet-index") <2>
-    .From(0)
-    .Size(10)
-    .Query(q => q
-        .Term(t => t.User, "stevejgordon") <3>
-    )
-);
-
-if (response.IsValid)
-{
-    var tweet = response.Documents.FirstOrDefault(); <4>
-}
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=search-tweet-fluent]
 ----
 <1> The generic type argument specifies the `Tweet` class, which is used when 
 deserialising the hits from the response.
@@ -126,59 +89,34 @@ aren't your thing.
 
 [source,csharp]
 ----
-var request = new SearchRequest("my-tweet-index") <1>
-{
-    From = 0,
-    Size = 10,
-    Query = new TermQuery("user") { Value = "stevejgordon" }
-};
-
-var response = await client.SearchAsync<Tweet>(request); <2>
-
-if (response.IsValid)
-{
-    var tweet = response.Documents.FirstOrDefault();
-}
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=search-tweet-object-initializer]
 ----
 <1> Create an instance of `SearchRequest`, setting properties to control the 
 search operation.
 <2> Pass the request to the `SearchAsync` method on the client.
 
 [discrete]
 [[updating-net]]
-==== Updating documents
+=== Updating documents
 
 Documents can be updated in several ways, including by providing a complete 
 replacement for an existing document ID.
 
 [source,csharp]
 ----
-tweet.Message = "This is a new message"; <1>
-
-var response = await client.UpdateAsync<Tweet, object>("my-tweet-index", 1, u => u
-        .Doc(tweet)); <2>
-
-if (response.IsValid)
-{
-    Console.WriteLine("Update document succeeded.");
-}
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=update-tweet]
 ----
 <1> Update a property on the existing tweet instance.
 <2> Send the updated tweet object in the update request.
 
 
 [discrete]
 [[deleting-net]]
-==== Deleting documents
+=== Deleting documents
 
 Documents can be deleted by providing the ID of the document to remove.
 
 [source,csharp]
 ----
-var response = await client.DeleteAsync("my-tweet-index", 1);
-
-if (response.IsValid)
-{
-    Console.WriteLine("Delete document succeeded.");
-}
+include::{doc-tests-src}/Usage/CrudExamplesTests.cs[tag=delete-tweet]
 ----

docs/usage/index.asciidoc

@@ -1,6 +1,7 @@
 [[usage]]
-== Using the .NET Client
+= Using the .NET Client
 
+[partintro]
 The sections below provide tutorials on the most frequently used and some less obvious features of {es}.
 
 For a full reference, see the {ref}/[Elasticsearch documentation] and in particular the {ref}/rest-apis.html[REST APIs] section. The {net-client} follows closely the JSON structures described there.

docs/usage/recommendations.asciidoc

@@ -1,11 +1,11 @@
 [[recommendations]]
-=== Usage recommendations
+== Usage recommendations
 
 To achieve the most efficient use of the {net-client}, we recommend following 
 the guidance defined in this article.
 
 [discrete]
-==== Reuse the same client instance
+=== Reuse the same client instance
 
 When working with the {net-client} we recommend that consumers reuse a single 
 instance of `ElasticsearchClient` for the entire lifetime of the application. 
@@ -22,7 +22,7 @@ by creating a singleton static instance or by registering the type with a
 singleton lifetime when using dependency injection containers.
 
 [discrete]
-==== Prefer asynchronous methods
+=== Prefer asynchronous methods
 
 The {net-client} exposes synchronous and asynchronous methods on the 
 `ElasticsearchClient`. We recommend always preferring the asynchronous methods,