UAIG and common terms:  Updated references per ReSpec method.

ReSpec-ified references in UAIG.
Updated common terms document's references such that they now work.
In two cases, used [[IAccessible2]] and [[UI-AUTOMATION]] instead
of [[IA2]] and [[UIA-ARIA]] based on listings in specref project:
https://github.com/tobie/specref, see biblio.json.

Tidied up the markup in the UAIG.