23.0.50; `mode-name' variable docs out of date WRT features

[sand]

Recent Emacs snapshots have extended the `mode-name' variable, so that
constructs such as

  '(sgml-xml-mode "XML" "SGML")

are allowed.  (See, for example, the definition of `sgml-mode'.)  The
documentation does not cover this list representation at all.  The
node "(elisp) Major Mode Conventions" states:

   * The major mode command should set the variable `mode-name' to the
     "pretty" name of the mode, as a string.  This string appears in the
     mode line.

and the node "(elisp) Mode Line Variables" states:

 -- Variable: mode-name
     This buffer-local variable holds the "pretty" name of the current
     buffer's major mode.  Each major mode should set this variable so
     that the mode name will appear in the mode line.

which implies (via "pretty") that this is a string, but doesn't
actually say what is allowed and what isn't.

The docs need to be updated to describe the new list-based
representation and how it is interpreted.

Derek