Add gemtext feature to docs

src/lib.rs

@@ -23,6 +23,10 @@
 //! users can access certain areas of an application.  This is primarily configured using
 //! the [`Server::ratelimit()`] method.
 //!
+//! * `gemtext` - Adds in integration with the `gemtext` crate, allowing easily creating
+//! responses using a builder pattern.  Please see the `document` example for a
+//! demonstration.  This is implied by `serve_dir` or `user_management_routes`
+//!
 //! * `serve_dir` - Adds in utilities for serving files & directories from the disk at
 //! runtime.  The easiest way to use this is to pass a [`PathBuf`] to the
 //! [`Server::add_route()`] method, which will either serve a directory or a single file.