[MINOR] Docs: remove incubator words - Docs: remove incubator words Author: Hao Chen <hchen9@ebay.com> Closes #967 from haoch/removeIncubatorWords. (cherry picked from commit 93095296a16a72986e04a9f720fc8d5a28a181fb) Signed-off-by: Hao Chen <hchen9@ebay.com>