While there, add a unit test to verify the behavior.
* doc/lispref/os.texi (Command-Line Arguments): Fix documentation: the
option string in 'command-switch-alist' does include leading hyphens.
Also mention that 'command-switch-alist' parsing ignores equals signs
in options.
* test/lisp/startup-tests.el
(startup-tests/command-switch-alist): New unit test.
