Update the Capture and Replay docs Mention that you must set ANGLE_CAPTURE_START_FRAME to 1 or greater. Bug: angleproject:6945 Change-Id: I3ff999749e62e1f4084656ada5d2f23c082641fe Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3413172 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Gregg Tavares <gman@chromium.org>