Add changelog

Author: Archmonger

docs/source/about/changelog.rst

@@ -23,6 +23,7 @@ Unreleased
 - :pull:`1118` - `module_from_template` is broken with a recent release of `requests`
 - :pull:`1131` - `module_from_template` did not work when using Flask backend
 - :pull:`1200` - Fixed `UnicodeDecodeError` when using `reactpy.web.export`
+- :pull:`1224` - Fixes needless unmounting of JavaScript components during each ReactPy render.
 
 **Added**