chore: update readme

Author: didinele

README.md

@@ -5,3 +5,17 @@
   </p>
   <br />
 </div>
+
+# Usage
+
+For folks with *write* access to `discordjs/discord.js`, by leaving a comment on any PR:
+
+```
+@discord-js-bot pack this
+```
+
+the bot should leave a 👀 reaction on your comment, after which a `publish-dev` workflow will be triggered. Once that's done,
+a comment will be left indicating success. If you receieve no feedback after a reasonable amount of time, it's possible the
+workflow failed, or that the bot is open.
+
+The bot can also be summoned by an existing comment via edits. Note that `@discord-js-bot pack this` must be the *start* of the comment.