Improve documentation of 'server-name'

* doc/emacs/misc.texi (Emacs Server, TCP Emacs server)
(emacsclient Options):
* lisp/server.el (server-name):  Document the usage of
'server-name' to specify the server file as an absolute file
name.  Do not merge to master.  (Bug#33934)
1 job for emacs-26 in 26 minutes and 44 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #450
test

00:26:44

 
Name Stage Failure
failed
test Test
Makefile:285: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:255: recipe for target 'check' failed
make[1]: *** [check] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:951: recipe for target 'check' failed
make: *** [check] Error 2
ERROR: Job failed: exit code 1