docs: prepare for RC 3 (#5713) * docs: prepare for RC 3 Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com> * docs: one more rc 3 update * chore: bump to 3.0.0rc3 Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com> --------- Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>