desk_templates: Add documentation for some of the views.

Some of the views are quite complex so add more class docs.

Test: none
Bug: none
Change-Id: Ifa71a123e3480229e6709e1eb94384cfa0c6f1ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3402416


Auto-Submit: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Richard Chui <richui@chromium.org>
Commit-Queue: Richard Chui <richui@chromium.org>
Cr-Commit-Position: refs/heads/main@{#962176}