Rollup merge of rust-lang#91192 - r00ster91:futuredocs, r=GuillaumeGomez

Some improvements to the async docs

The goal here is to make the docs overall a little bit more comprehensive and add more links between the things.

One thing that's not working yet is the links to the keywords. Somehow I couldn't get them to work.

r? ````@GuillaumeGomez```` do you know how I could get the keyword links to work?

Author: matthiaskrgr

library/core/src/future/future.rs

@@ -5,7 +5,7 @@ use crate::ops;
 use crate::pin::Pin;
 use crate::task::{Context, Poll};
 
-/// A future represents an asynchronous computation.
+/// A future represents an asynchronous computation obtained by use of [`async`].
 ///
 /// A future is a value that might not have finished computing yet. This kind of
 /// "asynchronous value" makes it possible for a thread to continue doing useful
@@ -23,6 +23,7 @@ use crate::task::{Context, Poll};
 /// When using a future, you generally won't call `poll` directly, but instead
 /// `.await` the value.
 ///
+/// [`async`]: ../../std/keyword.async.html
 /// [`Waker`]: crate::task::Waker
 #[doc(notable_trait)]
 #[must_use = "futures do nothing unless you `.await` or poll them"]

library/core/src/future/mod.rs

@@ -1,6 +1,13 @@
 #![stable(feature = "futures_api", since = "1.36.0")]
 
-//! Asynchronous values.
+//! Asynchronous basic functionality.
+//!
+//! Please see the fundamental [`async`] and [`await`] keywords and the [async book]
+//! for more information on asynchronous programming in Rust.
+//!
+//! [`async`]: ../../std/keyword.async.html
+//! [`await`]: ../../std/keyword.await.html
+//! [async book]: https://rust-lang.github.io/async-book/
 
 use crate::{
     ops::{Generator, GeneratorState},

library/std/src/keyword_docs.rs

@@ -2203,37 +2203,39 @@ mod where_keyword {}
 ///
 /// Use `async` in front of `fn`, `closure`, or a `block` to turn the marked code into a `Future`.
 /// As such the code will not be run immediately, but will only be evaluated when the returned
-/// future is `.await`ed.
+/// future is [`.await`]ed.
 ///
-/// We have written an [async book] detailing async/await and trade-offs compared to using threads.
+/// We have written an [async book] detailing `async`/`await` and trade-offs compared to using threads.
 ///
 /// ## Editions
 ///
 /// `async` is a keyword from the 2018 edition onwards.
 ///
-/// It is available for use in stable rust from version 1.39 onwards.
+/// It is available for use in stable Rust from version 1.39 onwards.
 ///
 /// [`Future`]: future::Future
+/// [`.await`]: ../std/keyword.await.html
 /// [async book]: https://rust-lang.github.io/async-book/
 mod async_keyword {}
 
 #[doc(keyword = "await")]
 //
 /// Suspend execution until the result of a [`Future`] is ready.
 ///
-/// `.await`ing a future will suspend the current function's execution until the `executor`
+/// `.await`ing a future will suspend the current function's execution until the executor
 /// has run the future to completion.
 ///
-/// Read the [async book] for details on how async/await and executors work.
+/// Read the [async book] for details on how [`async`]/`await` and executors work.
 ///
 /// ## Editions
 ///
 /// `await` is a keyword from the 2018 edition onwards.
 ///
-/// It is available for use in stable rust from version 1.39 onwards.
+/// It is available for use in stable Rust from version 1.39 onwards.
 ///
 /// [`Future`]: future::Future
 /// [async book]: https://rust-lang.github.io/async-book/
+/// [`async`]: ../std/keyword.async.html
 mod await_keyword {}
 
 #[doc(keyword = "dyn")]