Improve documentation of the 'function' special form

Point out that 'function' quoting is beneficial also for symbols.

* src/eval.c (function): Enhance docstring.
* doc/lispref/functions.texi (Anonymous Functions): Improve
documentation.
1 job for master in 53 minutes and 46 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Test
failed #1892
test-all

00:53:46

 
Name Stage Failure
failed
test-all Test
Makefile:318: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:293: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:957: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1