tlslite: document a couple of new parameters.

This is a followup to address some post-submit comments on
https://codereview.chromium.org/109563002/.

Comment only change. No semantic effect.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240907 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240907