Updated README w/ information about modules and KMP builds (#161)

* Updated README w/ information about modules and KMP builds

- included information about modules
- added badge for KDoc
- described how to add the dependency to KMP project
- explicitly specify the language for code snippets

Author: fzhinkin

README.md

@@ -3,8 +3,10 @@
 [![Kotlin Alpha](https://kotl.in/badges/alpha.svg)](https://kotlinlang.org/docs/components-stability.html)
 [![JetBrains incubator project](https://jb.gg/badges/incubator.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
 [![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-blue.svg?style=flat)](http://www.apache.org/licenses/LICENSE-2.0)
+[![Download](https://img.shields.io/maven-central/v/org.jetbrains.kotlinx/kotlinx-io-core/0.2.0)](https://central.sonatype.com/artifact/org.jetbrains.kotlinx/kotlinx-io-core/0.2.0)
 [![Kotlin](https://img.shields.io/badge/kotlin-1.8.21-blue.svg?logo=kotlin)](http://kotlinlang.org)
 [![TeamCity build](https://img.shields.io/teamcity/build/s/KotlinTools_KotlinxIo_BuildAggregated.svg?server=http%3A%2F%2Fteamcity.jetbrains.com)](https://teamcity.jetbrains.com/viewType.html?buildTypeId=KotlinTools_KotlinxIo_BuildAggregated&guest=1)
+[![KDoc link](https://img.shields.io/badge/API_reference-KDoc-blue)](https://fzhinkin.github.io/kotlinx-io-dokka-docs-preview/)
 
 A multiplatform Kotlin library providing basic IO primitives. `kotlinx-io` is based on [Okio](https://github.com/square/okio) but does not preserve backward compatibility with it.
 
@@ -17,23 +19,42 @@ The library is built around `Buffer` - a mutable sequence of bytes. `Buffer` wor
 
 The library also provides interfaces representing data sources and destinations - `Source` and `Sink`.
 
+In addition to `Buffer`, the library provides an immutable sequence of bytes - `ByteString`.
+
+There are two `kotlinx-io` modules:
+- [kotlinx-io-bytestring](./bytestring) - provides `ByteString`.
+- [kotlinx-io-core](./core) - provides IO primitives (`Buffer`, `Source`, `Sink`), depends on `kotlinx-io-bytestring`.
+
 ## Using in your projects
 
 > Note that the library is experimental, and the API is subject to change.
 
 ### Gradle
 
 Make sure that you have `mavenCentral()` in the list of repositories:
-```
+```kotlin
 repositories {
     mavenCentral()
 }
 ```
 
 Add the library to dependencies:
-```
+```kotlin
 dependencies {
-    implementation("org.jetbrains.kotlinx:kotlinx-io:0.2.0-alpha-dev1")
+    implementation("org.jetbrains.kotlinx:kotlinx-io-core:0.2.0")
+}
+```
+
+In multiplatform projects, add a dependency to the `commonMain` source set dependencies:
+```kotlin
+kotlin {
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation("org.jetbrains.kotlinx:kotlinx-io:0.2.0")
+            }
+        }
+    }
 }
 ```
 
@@ -43,8 +64,8 @@ Add the library to dependencies:
 ```xml
 <dependency>
     <groupId>org.jetbrains.kotlinx</groupId>
-    <artifactId>kotlinx-io</artifactId>
-    <version>0.2.0-alpha-dev1</version>
+    <artifactId>kotlinx-io-core</artifactId>
+    <version>0.2.0</version>
 </dependency>
 ```