commands: document module

src/commands.rs

@@ -1,3 +1,12 @@
+//! Module containing the basic building blocks, definitions and helpers
+//! for implementing an MPD command. A command consists of a pair of serializers
+//! and parsers for both the request and the corresponding response, as well as
+//! the command name used to identify the command.
+//!
+//! Each command is modelled as a struct implementing the [`Command`] trait,
+//! which in turn uses the [`CommandRequest`] and [`CommandResponse`] traits
+//! to define the request and response types respectively.
+
 use crate::{request_tokenizer::RequestTokenizer, response_tokenizer::ResponseAttributes};
 
 mod audio_output_devices;