Fix some old and annoying doc problems.

Javadocs don't like comments that have no "." at the end (they will
continue to read more until they find one). So many of the docs
in attrs show up with descriptions that include the dimension format
info... as part of their one-sentence synopsis.

Also, "e.g." confuses javadoc because it brings the sentence to a close
(in the middle).

Also, some attrs lack docs entirely, which has the unfortunate result
of the javadocs having only the format description, which looks pretty
silly. I fixed a small number of these.

Bug: 35834231  clean up bad attr docs
Test: no test, docs only. But I did a docs build and it worked.
Change-Id: Ia7bc49a5084a7be2839b1aa521e53b73a08ac985