docs: Document feature flags (#1003)

README.md

@@ -463,6 +463,11 @@ The prost project maintains flakes support for local development. Once you have
 nix and nix flakes setup you can just run `nix develop` to get a shell
 configured with the required dependencies to compile the whole project.
 
+## Feature Flags
+- `std`: Enable integration with standard library. Disable this feature for `no_std` support. This feature is enabled by default.
+- `derive`: Enable integration with `prost-derive`. Disable this feature to reduce compile times. This feature is enabled by default.
+- `prost-derive`: Deprecated. Alias for `derive` feature.
+- `no-recursion-limit`: Disable the recursion limit. The recursion limit is 100 and cannot be customized. 
 
 ## FAQ
 

prost-build/src/lib.rs

@@ -82,6 +82,10 @@
 //! That's it! Run `cargo doc` to see documentation for the generated code. The full
 //! example project can be found on [GitHub](https://github.com/danburkert/snazzy).
 //!
+//! ## Feature Flags
+//! - `format`: Format the generated output. This feature is enabled by default.
+//! - `cleanup-markdown`: Clean up Markdown in protobuf docs. Enable this to clean up protobuf files from third parties.
+//!
 //! ### Cleaning up Markdown in code docs
 //!
 //! If you are using protobuf files from third parties, where the author of the protobuf

prost-types/src/lib.rs

@@ -7,6 +7,9 @@
 //!
 //! See the [Protobuf reference][1] for more information about well-known types.
 //!
+//! ## Feature Flags
+//! - `std`: Enable integration with standard library. Disable this feature for `no_std` support. This feature is enabled by default.
+//!
 //! [1]: https://developers.google.com/protocol-buffers/docs/reference/google.protobuf
 
 #![cfg_attr(not(feature = "std"), no_std)]