DOC: Move ecosystem.rst to getting started section
So it makes `ecosystem` discoverable from the docs navigation.

Also removes an unused tips.csv and `ipython_warning_is_error` (which is enforced by our build error on warnings)
Agreed with only keeping the website version of the ecosystem docs. I unioned the two and fixed the old references we had to the `rst` version Going to merge this cleanup, but happy to address any followups