Get all the knowledge related to OONI into the wiki

There is now a wiki on trac that will be used as a knowledge base for OONI: https://trac.torproject.org/projects/tor/wiki/doc/OONI.

We should start collecting all OONI related information there. This includes:

#5866 (closed) - Research on test to write (https://trac.torproject.org/projects/tor/wiki/doc/OONI/Tests)

#5867 (closed) - Devise methodology taxonomy (https://trac.torproject.org/projects/tor/wiki/doc/OONI/Methodology)

#5865 (closed) - Evaluate other tools and solutions (TODO)

#5864 (closed) - General Research Methodology (https://trac.torproject.org/projects/tor/wiki/doc/OONI/Methodology)

#5906 (closed) - Evaluate the OONI Architecture design (https://trac.torproject.org/projects/tor/wiki/doc/OONI/Architecture)

#5907 (closed) - Design the OONI Backend (https://trac.torproject.org/projects/tor/wiki/doc/OONI/Backend)