Add polybar-msg same-user restriction to changelog

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - We added the backslash escape character (\\) for configuration values. This means that the literal backslash character now has special meaning in configuration files, therefore if you want to use it in a value as a literal backslash, you need to escape it with the backslash escape character. The parser logs an error if any unescaped backslashes are found in a value. This affects you only if you are using two consecutive backslashes in a config value, which will now be interpreted as a single literal backslash. ([`#2354`](https://github.com/polybar/polybar/issues/2354))
 - We rewrote our formatting tag parser. This shouldn't break anything, if you experience any problems, please let us know. The new parser now gives errors for certain invalid tags where the old parser would just silently ignore them. Adding extra text to the end of a valid tag now produces an error. For example, tags like `%{T-a}`, `%{T2abc}`, `%{rfoo}`, and others will now start producing errors. This does not affect you unless you are producing your own invalid formatting tags (for example in a script).
 - For security reasons, the named pipe at `/tmp/polybar_mqueue.<PID>` had its permission bits changed from `666` to `600` to prevent sending ipc messages to polybar processes running under a different user.
+- Also for security reasons, the `polybar-msg` command will now only send messages to polybar processes running under the same user. See the [IPC documentation](https://polybar.readthedocs.io/en/stable/user/ipc.html) for what exactly this means.
 
 ### Build
 - New dependency: [libuv](https://github.com/libuv/libuv). At least version 1.3 is required.