doc: Add placeholders for unindexed methods

Not having a description yet is fine, but they should at least
be indexed as blocks so that they are searchable and listed
in the jsduck generated pages. jsduck defaults to @method + name
of prototype property. And it even guesses parameters sometimes.

Search: \n\n([a-zA-Z\.]+\.prototype\.[a-zA-Z]+)
Where: modules/ve,modules/ve-mw
Where-Not: modules/ve/test
Replace: \n\n/** */\n$1

Added @return in a few places where it was easy to add.

Change-Id: I830c94cc7dbc261bd7a077391f930cbfff165f9d