bug#7521: 24.0.50; doc for `delimit-columns-*'

[Drew Adams]

emacs -Q

You cannot understand a thing about commands `delimit-columns-region'
and `delimit-columns-rectangle' without reading the commentary in Lisp
file delim-col.el.  In sum, there is no help for users - no doc.

Not only that, if you are tempted to try these commands on a regular
region of text, you will likely see no change at all - the buffer isn't
even modified.  This is because these commands only affect regions and
rectangles that contain text formatted in a certain way.

This is all explained in detail in the source file commentary,
`delim-col.el'.  But none of it is available to users via *Help*.

Similarly, the defcustoms are little help.  They explain nothing.  Users
must consult the source file to understand _anything_ about this feature.

In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2010-11-22 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.4) --no-opt --cflags
-Ic:/imagesupport/include'