Add no emojis rule

Author: nmarley

commands/start.md

@@ -39,6 +39,8 @@ You have access to the `gh` CLI for GitHub and the `glab` CLI for GitLab, if app
 You may use READ-ONLY commands for any of these if the user requests something related to this.
 
 It is _critical_ that if you are asked to make any database changes or migrations, remember that you must never, ever run the migrations yourself, unless the user specifically asks you to. Otherwise, you **must** leave the migrations for the user to run.
+
+And FFS, no emojis in any documents you've been asked to create / generate, unless you're absolutely explicitly requested to add them.
 </additional_instructions>
 
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