Fix the broken link to documentation on DumpAccessibilityTree. Update
to use relative urls in the links to the other docs so that they can be
viewed within a commit.
Change-Id: I3083bd75a01ea267cba0fc7a654fd2d0d4a1599f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3942956
Reviewed-by: Katie Dektar <katie@chromium.org>
Commit-Queue: Kyungjun Lee <kyungjunlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1057160}