Log Message:
gnucash-docs: update to 4.6.

Concurrent with the release of GnuCash 4.6 we're pleased to also release a new \ 
version of the companion Help and Tutorial and Concepts Guide
Between 4.5 and 4.6, the following bugfixes were accomplished:

    Bug 798178 - : Wrong Color in Scheduled Transactions Window text
    Bug 798217 - minor mistakes in Tutorial and Concepts guide

The following fixes and improvements were not associated with bug reports:

    Update ch_invest.xml
    Help/C: New screenshots, remove unused images, and image optimization
    New help/de/figures/Main-window-callouts + helper files
    Add ENTITY vers-last-2 for reference of major changes
    Make calibre optional in cmake
    Create Github actions to replace TravisCI
    Fixes reference to Help Manual
    Help: link Setup for Online Transactions in C, de
    Help: Replace most <literallayout> by <screen>
    Help pt: Add missing xmlns:xi parameters
    Replace most <literallayout> by <screen>; <screen> uses \ 
Monospace while <literallayout> keeps the default (proportional) font
    Backport of improvements from de/Help_ch_GUIMenus.xml
        Added new menu items
        Corrected the order of menu items
        Removed duplicate descriptions
        insert <accel>-Tags
    Update PACKAGE_URL of configure.ac
    xmlformat all docs
    EEC became EU decades ago, but we had still references
    Several fixes of shortcuts in C and pt
    Check for " >" to avoid unwanted wraps
    Add xmlformat incl. configuration
    Improve the wiki link in the note for translators