Document use of "View tag" in template selection

After upgrading to Views 2.6, several of my views started displaying differently, because they found templates files matching their "view tag" (templates that I wasn't intending them to use!) See #354270: Allow Views Templates to Affect Views Output by Tag

Can you please document this new behavior?

In particular, the help text when entering a view tag says: "Enter an optional tag for this view; it is used only to help sort views on the administrative page." That's simply not true any more.

Maybe it should say something like "... it is used to help sort views on the administrative page and in selecting a template file for displaying this view."