Fix up for numbered headings for Western Arabic (#16575)
Fixup of #16425
Discussed here: groups.io/g/nvda-translations/message/3819
Summary of the issue:
In 2023.2, the user guide heading numbering for the Arabic translation switched to using Western Arabic numbering.
2024.1 mistakenly switched this back to Eastern Arabic numbering.
In #16425, the headers in the table of contents were fixed for Western Arabic, but not in the body.
Description of user facing changes
Restore Western Arabic numbering style for headings in the body of the document
Description of development approach
Updated CSS to reflect Western Arabic numbering style i.e. .1.2.3, .1.2.4
