doc: Add note about Python symlinks (PR 2362) to CHANGELOG.md for 9.1.0

The PR for this change was merged without a prefixed name,
such as "lib:" or "fix:". That means release-please
didn't include it in the changelog for v9.1.0.

This change did end up affecting users, though. (See issue 2713
and PR 2721). Therefore, I believe it should be noted
in the CHANGELOG.md, so users can better understand the behavior
they are seeing.

Author: DeeDeeG

CHANGELOG.md

@@ -68,6 +68,7 @@
 ### Core
 
 * update due to rename of primary branch ([ca1f068](https://www.github.com/nodejs/node-gyp/commit/ca1f0681a5567ca8cd51acebccd37a633f19bc6a))
+* Add Python symlink to path (for non-Windows OSes only) ([#2362](https://github.com/nodejs/node-gyp/pull/2362)) ([b9ddcd5](https://github.com/nodejs/node-gyp/commit/b9ddcd5bbd93b05b03674836b6ebdae2c2e74c8c))
 
 
 ### Tests