[meta] Added CHANGES item for the help screen.

Changed codename, seems more temporally fitting.

CHANGES.md

-# jsCoq 0.16.0 "To plugin or not to plugin"
+# jsCoq 0.16.0 "Paris-bound"
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- - Update to Coq 8.16.0 (@corwin-of-amber, @ejgallego)
- - Now Coq loads plugins using findlib, but we don't yet support that
+ - Update to Coq 8.16.0. (@corwin-of-amber, @ejgallego)
+ - Now Coq loads plugins using findlib, but we don't yet support that;
+   most plugins can still load in legacy mode.
  - Port the JS codebase to ES modules (@ejgallego, #276)
+ - Add a quick help screen in the UI (@corwin-of-amber, #290)
 
 # jsCoq 0.15.1 "Go For Your Toad, or Similar"
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