Updated CHANGELOG.md for 2.9.0 release

Updated CHANGELOG.md for 2.8.6 release

Updated CHANGELOG.md for 2.7.2 release

Updated CHANGELOG.md for 2.6.2 release

Updated CHANGELOG.md for 2.5.3 release

Updated CHANGELOG.md for 2.4.2 release

Updated CHANGELOG.md for 2.3.4 release

Updated CHANGELOG.md for 2.2.2 release

Updated CHANGELOG.md for 2.1.1 release

docs: remove syncfusion as higher tier sponsor from index.md

Removed Syncfusion sponsorship link from the index page.