bug#23392: 25.1.50; [wishlist] Somebody should clean up the "*" in doc strings

[Glenn Morris]

As of now, the only remaining issue (outside lisp/obsolete/) is a bunch
of Gnus defvoo's with leading "*" in the doc. These expand to defvars.
Either the leading * should be removed, or they should expand to
defcustoms. Rough count:

./gnus/nndiary.el 1
./gnus/nndir.el 1
./gnus/nndoc.el 2
./gnus/nnrss.el 1
./gnus/nnspool.el 1
./gnus/nntp.el 33