Adding sphinxcontrib-confluencebuilder to the supported extensions

[jmpicnic]

First of all, thanks a lot for your work on this plug-in

Would it be possible to add sphinxcontrib-confluencebuilder to the bundled extensions? (https://sphinxcontrib-confluencebuilder.readthedocs.io/en/stable/configuration/)

Alternatively, would it be possible to have a way to add additional extensions to the plug-in?

Looking at the code, it seems that the only file that would need changing would be:

2-install-pkgs.sh

@@ -24,6 +24,7 @@ pip install \
   'git+https://github.com/sphinx-contrib/youtube.git@635c8a908e3cac552ce43293c1516e7270cc4ce8#egg=sphinxcontrib.youtube' \
   'sphinxemoji==0.1.8' \
   'sphinx-markdown-tables==0.0.15'
+  'sphinxcontrib-confluencebuilder==1.7.1'

plus the tests and readme.

Thanks a lot for any help. I'd be glad to contribute a PR if needed. I don't have easy access to a travis builder, so I can't test the build myself.

Thanks

Miguel

[miurahr]

You can put your extension files in _extentions/ copied from venv/lib/ and point it in conv.py.