doc: Update CONTRIBUTORS Added a number of names that were missing from CONTRIBUTORS. Bug: angleproject:1944 Change-Id: I5e8e2d13494b5ded7dec7a094218e4aef90d9da3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2235931 Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Tobin Ehlis <tobine@google.com>