[PR fortran/89348, patch] Fortran Command Options documentation fixes

[Mark Eggleston]

Enabling of -fdec-include is missing from list of options enabled by 
-fdec. When rendered as a PDF some lines are too long in the list of 
options controlling Fortran dialect and in the list of options to 
request or suppress errors and warnings.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89348
Patch and change log attached to PR.

OK for trunk? I do not have commit rights.

--
https://www.codethink.co.uk/privacy.html