Including release-notes/next directory for accumulating release notes

Also include a retroactive release note for PR #789

release-notes/next/789.txt

@@ -0,0 +1,4 @@
+Type: Fix
+Public: Yes
+GHI: https://github.com/plexinc/plex-media-player/pull/789
+Release Notes: Fix window icon on Linux

release-notes/next/example.txt

@@ -0,0 +1,11 @@
+Type: Feature | Fix | Refactor
+Public: Yes | No
+GHI: https://github.com/plexinc/plex-media-player/issues/0000
+Release Notes: Fixed the thing | Added the thing
+
+Glossary:
+- Feature: Something was added that was not there before
+- Fix: Something was broken and is now fixed
+- Refactor: Nothing was added, removed, or changed, but code was refactored
+- GHI: The backing GitHub Issue or Pull Request if a GHI does not exist
+- Release Notes: The one line description describing the change