[cairo] Change proposal for pycairo pages on cairographics.org

[Christoph Reiter]

Hey,

with the move of pycairo to GitHub the pycairo website requires an update and
it was suggested that I propose this on the mailing list.

The update would affect /pycairo, /pycairo/tutorial and /pycairo/resources
and would look like this:

https://imgur.com/a/ycey1

Since I use readthedocs for automatically building the documentation from
GitHub, the official tutorial, API docs etc would move from

https://cairographics.org/documentation/pycairo/

to

https://pycairo.readthedocs.io

Any thoughts, objections?

regards