LP#1413624 Docs: Move Access Handler docs to official docs

LP#1413624 Docs: Move Access Handler docs to official docs

This commit moves the new Access Handler doc file to the official docs
folder, adds the file reference to the root.txt, changes the main header
text for easier linking, adds the missing block delimiter lines around a
code block, and adds a blank line at the end of another doc file to
prevent the docs from running together.

Signed-off-by: Remington Steed <rjs7@calvin.edu>