Add documentation for the PrefixGetter trait

src/framework/bot.rs

@@ -27,8 +27,23 @@ pub enum RuntimeError {
     ApplicationFetchingFailed,
 }
 
+/// Getter trait for command prefixes.
 #[async_trait]
 pub trait PrefixGetter<T> {
+    /// Get the command prefixes for the given server and user IDs.
+    /// 
+    /// The getter must never fail. In case an internal process does, it must fall back to default
+    /// prefixes.
+    ///
+    /// Arguments:
+    /// * `runtime` - The application [`Runtime`].
+    /// * `server_id` - The server ID in which the command, interaction, or event is running.
+    /// * `user_id` - The user ID who triggered the command, interaction, or event.
+    ///
+    /// Returns:
+    /// [`Vec<String>`] - A list of command prefixes. When matching for commands, all these
+    /// prefixes should be checked against, as they're all valid. In case one should be picked, the
+    /// first one will always be the safest choice.
     async fn get(
         &self,
         runtime: &Runtime<T>,