The charts were regenerated, update the docs to point to the new charts.
Also remove some redundancy (we don't need the overview to track differences in vendors)

Bug: angleproject:3713
Change-Id: I2005031c4ca960d7f9afd80562957d31af795d61
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1721190Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>