gnucash-docs maint: Enhance bookinfos by subtitle and titleabbrev; drop "Help" from manual

[Frank H.Ellenberger]

Updated	 via  https://github.com/Gnucash/gnucash-docs/commit/62327bb2 (commit)
	from  https://github.com/Gnucash/gnucash-docs/commit/540f0cef (commit)



commit 62327bb26201d51b8158308865cf957635ce8df1
Author: Frank H. Ellenberger <frank.h.ellenberger at gmail.com>
Date:   Sat Oct 22 14:55:01 2022 +0200

    Enhance bookinfos by subtitle and titleabbrev;drop "Help" from manual
    
    titleabbrev allows yelp to display the version in its titlebar



Summary of changes:
 guide/C/index.docbook  | 8 +++++---
 manual/C/index.docbook | 8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)