Add a few words about governance to the CONTRIBUTING guideline

[jgrewe]

convert README to md

[coveralls]

Coverage remained the same at 77.232% when pulling f0995d2 on jgrewe:gov into ac805c5 on G-Node:master.

[achilleas-k]

I remember that the reason we changed READMEs in our Python projects to reStructuredText was because PyPI wasn't rendering Markdown. Checked to see if the new PyPI does and it seems that it supports md now too (or maybe it did before as well and we missed it), but the setup.py needs to specify it:

By default, an upload's description will render with reStructuredText. If the description is in an alternate format like Markdown, a package may set the long_description_content_type in setup.py to the alternate format.

Source https://pypi.org/help/#description-content-type

[jgrewe]

Thanks for remembering. Thought it was for purely historical reasons.
Since we have everything else as markdown I thought it plausibel...
I can revert that or try to specify that we use md. What would you prefer ?

[achilleas-k]

Now that we know how to get PyPI to render md, I think we should make everything md. At least for me, it's more convenient, and we always default to md anyway.