Bring back mention of NNTP gmane

Problem reported by Michael Albinus at:
https://lists.gnu.org/r/emacs-devel/2019-09/msg00519.html
* admin/notes/emba: Reintroduce mention of nttp+news.gmane.org,
since that still works.
1 job for master in 78 minutes and 31 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #3445
test-all

01:18:31

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