bug#3393: 23.0.94; Document lisp-indent-function in Elisp manual

Shouldn't `lisp-indent-function' be documented - with perhaps an
example of using the symbol property? The question pops up in
help-gnu-emacs from time to time of how to specify the indentation to
use for some form. There is no how-to doc to point users to.
 
Actually, there is some (very incomplete) mention of it in the Emacs
manual (which might not make much sense, since you need to code Lisp
to use this), in node Lisp Indent. The help given there is inadequate
for you to figure out how to actually use this.
 

In GNU Emacs 23.0.94.1 (i386-mingw-nt5.1.2600)
 of 2009-05-24 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'