update & refresh links

* Replace "master" with "HEAD".
* Use https:// in a lot of places.
* Use crbug.com as a shortcut.
* Update some dead links.
* Drop the chromiumos/docs/ prefix on a lot of files.

Change-Id: I9ef52e8b4e3c8c86678edf7a92c0b368874cfd0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/docs/+/2393474
Reviewed-by: Bernie Thompson <[email protected]>
Commit-Queue: Mike Frysinger <[email protected]>
Tested-by: Mike Frysinger <[email protected]>
diff --git a/README.md b/README.md
index 3ede886..258416a 100644
--- a/README.md
+++ b/README.md
@@ -65,12 +65,12 @@
 
 [Chromium OS]: https://www.chromium.org/chromium-os
 [Contributing]: contributing.md
-[rendered by Gitiles]: https://chromium.googlesource.com/chromiumos/docs/+/master/
+[rendered by Gitiles]: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/
 [Gerrit sandbox branches]: contributing.md#sandbox
-[Gitiles-flavored Markdown]: https://gerrit.googlesource.com/gitiles/+/master/Documentation/markdown.md
-[Chromium documentation guidelines]: https://chromium.googlesource.com/chromium/src/+/master/docs/documentation_guidelines.md
-[Chromium documentation best practices]: https://chromium.googlesource.com/chromium/src/+/master/docs/documentation_best_practices.md
+[Gitiles-flavored Markdown]: https://gerrit.googlesource.com/gitiles/+/HEAD/Documentation/markdown.md
+[Chromium documentation guidelines]: https://chromium.googlesource.com/chromium/src/+/HEAD/docs/documentation_guidelines.md
+[Chromium documentation best practices]: https://chromium.googlesource.com/chromium/src/+/HEAD/docs/documentation_best_practices.md
 [style guide]: https://github.com/google/styleguide/tree/gh-pages/docguide
 [repo]: https://source.android.com/source/using-repo
 [chromium-review.googlesource.com]: https://chromium-review.googlesource.com/
-[md_browser]: https://chromium.googlesource.com/chromium/src/tools/md_browser/+/master/
+[md_browser]: https://chromium.googlesource.com/chromium/src/tools/md_browser/