release: cut the 5.1.0-beta.2 release

docs: add changelog for 5.0.3

docs: add changelog for 5.1.0-beta.1

docs: add changelog for 5.0.2

docs: add changelog for 5.1.0-beta.0

docs: add changelog for 5.0.1

docs: add changelog for 5.0.0

docs: add changelog for 5.0.0-rc.9

docs: add changelog for 5.0.0-rc.8

docs: add changelog for 5.0.0-rc.7