Add option for navigation depth

[agjohnson]

Fixes #277

[akien-mga]

Thanks! Would this option be accessible from conf.py when using sphinx_rtd_theme installed system-wide, or does one need a custom copy of it to modify the theme.conf file?

[agjohnson]

@akien-mga You can set options in conf.py, see http://www.sphinx-doc.org/en/stable/config.html#confval-html_theme_options

[akien-mga]

@agjohnson Thanks, that was my understanding but I tried this for collapse_navigation recently and it did not seem to work: godotengine/godot-docs@8976f4d
Or do I have a syntax error?

Edit: Ok I guess I should not have written my boolean as a string, sorry for the noise :p

[akien-mga]

Hm even after fixing my syntax error the option doesn't seem to be taken into account. Any clue as to what I'm doing wrong?

Edit: Alright, sorry for the noise again. It looks like the proper option that I want is 'collapse_navigation': False, i.e. the same as the default one, but apparently not the default on ReadTheDocs.