Add instructions on how to run glmark2+ANGLE on Linux
Add instructions on how to run glmark2+ANGLE on Linux

Bug: angleproject:3125
Change-Id: I70d295d7ec1dbafc74add068165c5fbcadb48560
Reviewed-on: https://chromium-review.googlesource.com/c/1450222
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle