docs: Update changelog with changes since 5.0-rc1.
docs: Update changelog with changes since 5.0-rc1.

kou/zulip,kou/zulip,rht/zulip,andersk/zulip,kou/zulip,zulip/zulip,zulip/zulip,andersk/zulip,andersk/zulip,zulip/zulip,zulip/zulip,zulip/zulip,rht/zulip,zulip/zulip,kou/zulip,kou/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,rht/zulip,rht/zulip,rht/zulip,rht/zulip,rht/zulip,kou/zulip,andersk/zulip,kou/zulip