ext:documentation should accept lowercase index.html as main file
Currently main file must be Index.html
This prevents using html export of other applications (e.g. from a wiki) as additional documentations because often lowercase index.html filename or even index.htm is used.
[BUGFIX] EXT:documentation should accept other index file names
EXT:documentation checks for Index.html, index.html and index.htm as
main files for additional html documentations.
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn