doc: add rust-std chapter to book

Author: phip1611

book/src/SUMMARY.md

@@ -10,6 +10,7 @@
   - [Using Protocols](how_to/protocols.md)
   - [Drawing to the Screen](how_to/drawing.md)
   - [Building drivers](how_to/building_drivers.md)
+  - [Combining Rust `std` with `uefi`](how_to/rust-std.md)
 - [Concepts](concepts/introduction.md)
   - [Boot Stages](concepts/boot_stages.md)
   - [Tables](concepts/tables.md)

book/src/how_to/rust-std.md

@@ -0,0 +1,29 @@
+# Combining Rust `std` with `uefi`
+
+## TL;DR
+
+In Mid-2024, we recommend to stick to our normal guide. Use this document as
+guide and outlook for the future of UEFI and Rust.
+
+## About
+
+Programs created with the `uefi` crate are typically created with `#![no_std]`
+and `#![no_main]`. A `#![no_std]` crate can use the `core` and `alloc` parts of
+Rust's standard library, but not `std`. A `#![no_std]` executable does not use
+the standard main entry point, and must define its own entry point; `uefi`
+provides the `#[entry]` macro for this purpose.
+
+Rust has added partial support for building UEFI executables without
+`#![no_std]` and `#![no_main]`, thus, the standard way. Some functionality
+requires a nightly toolchain, they are gated by the `uefi_std` feature (Rust
+language feature, not `uefi` crate feature). Follow the
+[tracking issue](https://github.com/rust-lang/rust/issues/100499) for details.
+
+## Code Example
+
+Please refer to [`<repo>/uefi-std-example`](/uefi-std-example/README.md) to
+see a specific example. The relevant `main.rs` looks as follows:
+
+```rust
+{{#include ../../../uefi-std-example/src/main.rs}}
+```