bug#14801: 24.3.50; Document monitor attributes (e.g., `workarea' and `mm-size')

[Drew Adams <drew.adams@oracle.com>]

Monitor attributes are partially documented in
`C-h f display-monitor-attributes-list'.  They should also be (fully)
documented in the Elisp manual.

Even in the doc string of d-m-a-l, the description is incomplete and
needs to be filled out.

Attribute `workareas' is described only in terms of "the workarea".
There is no explanation of what is meant by "workarea" (which should
presumably be two words, BTW).

Attribute `mm-size' is described only as "the width and height in
millimeters".  It's all very nice to say what the units are, but what is
it that is being measured?  The width & height of what?  If it is the
"work area" (whatever that might be) then say so explicitly.

Beyond all this, what on Earth IS a monitor "attribute"?  Is it supposed
to be the same thing as a frame parameter?  The Elisp manual covers file
attributes and face attributes.  And it mentions terminal attributes (in
passing - there is no explanation or description of them), but it is
silent about monitor attributes.

The doc for this feature or collection of features (?) is hopelessly
incomplete and confused.  One can only make wild guesses as to what is
meant and what this is all about.

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-07-01 on LEG570
Bzr revision: 113246 lekktu@gmail.com-20130701165437-ea20s94hqwp3ttaj
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/usr --enable-checking CFLAGS='-O0 -g3'
 CPPFLAGS='-DGLYPH_DEBUG=1 -I/c/usr/include''