doc: Update buildbot URL
doc: Update buildbot URL

Change-Id: I7a1b6b91cb3f549904e2b930dab8becaca13085c
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2144915
Reviewed-by: Joshua Peraza <f5809a5e35ec7e1bd0e25cb0a0b68bb433cf6f17@chromium.org>
Commit-Queue: Mark Mentovai <f1b5a91d4d6ad523f2610114591c007e75d15084@chromium.org>

chromium/crashpad,chromium/crashpad,chromium/crashpad