"Title underline too short" warning in a lot of API docs

[yousefmoazzam]

From browsing the various warnings in the docs build (noted in #468), I noticed these types of warnings for basically every module in httomo:

:mod:`httomo.sweep_runner.param_sweep_yaml_loader`
============================================
/dls/science/users/twi18192/httomo/docs/source/api/httomo.sweep_runner.side_output_manager.rst:2: WARNING: Title underline too short.

It seems this is due to the hardcoded length of the underline in the template used to generate the API docs rst files from*:

httomo/docs/source/_templates/module.rst_t

Lines 1 to 7 in 18c2e04

	{%- if show_headings %}:mod:`{{ basename }}`
	============================================
	{%- endif %}
	.. automodule:: {{ qualname }}
	{%- for option in automodule_options %}
	:{{ option }}:
	{%- endfor %}

*The -t flag in the docs build script is providing that template I think:

httomo/docs/sphinx-build.sh

Line 28 in 18c2e04

sphinx-apidoc -feT -t=$DIR/source/_templates -o $DIR/source/api $DIR/../httomo