[stable20.1] Add changelog for 9.0.8, 10.0.6 and 10.1.2

[nickvergessen]

10.1.2 – 2021-02-22

✅ Added

• Added pagination to the gridview in case there are too many participants #4991

🔧 Changed

• Replace blur with average color in video backgrounds to improve performance on Chrome based browsers #5011
• Allow SIP dial-in in non-public conversations too #4955

🐞 Fixed

• Drop guest moderators when changing a conversation to group conversation #5231
• Fix collaboration resource options not loading #5141
• Fixed a bug that would prevent attachments going into the Talk/ folder #5078
• Fix mentioning of users with subnames, e.g. "foo" and "foobar" #5050
• Add upload editor in files sidebar mode #5113

[PVince81]

👍