This CL updates the tool instructions to reflect changes in the tool.
Removes the empty <br> tags from the tool's panel templates.

Bug: v8:10644, v8:10727

Change-Id: I0b3db6adcd37518f9cdaf2839094ef86eff52dfb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2413253Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Zeynep Cankara <zcankara@google.com>
Cr-Commit-Position: refs/heads/master@{#69963}