composer/composer#7384: update chat note based on code review feedback

Co-Authored-By: dmanners <dmanners87@gmail.com>

doc/04-schema.md

@@ -243,7 +243,7 @@ Support information includes the following:
 * **source:** URL to browse or download the sources.
 * **docs:** URL to the documentation.
 * **rss:** URL to the RSS feed.
-* **chat:** URL to chat server.
+* **chat:** URL to the chat channel.
 
 An example: