Update README about GLES1 Bug: angleproject:1944 Change-Id: I7dd47e76a59da9f3d0f43c8e802e1c335dcf7213 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4158231 Reviewed-by: Cody Northrop <cnorthrop@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: mohan maiya <m.maiya@samsung.com>