Pin Sphinx version for readthedocs to prevent #379

[adswa]

ATM we don't have a readthedocs.yml file, and Readthedocs builds the handbook with the most recent Sphinx release (2.3.1). I believe that this version leads to a tiny bug, described in #379. By pinning Sphinx to an earlier version in requirements.txt and providing a readthedocs.yml file, I hope to get rid of the broken meta property tag.

Hopefully fixes #379.

[adswa]

An alternative "fix" would be to remove the line in the layout template that suffers from the change in the most recent Sphinx version:

book/docs/_templates/layout.html

Line 31 in 6be555d

<meta property="og:title" content="{{ title }}{{ titlesuffix }}">

(the problem is the "title" template -- it includes a 1. around the section number now, which is what breaks things)

[adswa]

I'll see whether this yaml file works. Its recommended by rdt to have a yml file anyway, and I want the broken tag to not be displayed on every html page anymore.

[adswa]

Wonderful, this worked.

[adswa]

Ha, I take this back. The builds currently fail because requirements.txt does not specify dataladhandbook_support (which is to be installed with pip install -e . in the repo). I need to find out how to specify this in requirements or revert this and get rid of the meta tag in the template...