Fix documentation of '-position' server command

* lisp/server.el (server-process-filter): Fix the description
of "-position" command to match the reality.  (Bug#38443)
1 job for master in 87 minutes and 59 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #4450
test-all

01:27:59

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:319: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1