WinGui: Some minor updates to the doc's texi files.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6441 b64f7644-9d1e-0410-96f1-a4d463321fa5
Some more doc updates.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6442 b64f7644-9d1e-0410-96f1-a4d463321fa5