[community] suggested glossary additions

[Alison Macrina]

Taylor Yu:
> Hi Community Team,
> 
> Here are some of my suggested additions to the glossary page at
> https://trac.torproject.org/projects/tor/wiki/doc/community/glossary
> that could be helpful to new contributors (or maybe just people
> interested in the project):
> 
> === GSoC ===
> Tor participates in the Google Summer of Code, which is a summer program
> for university students.
> 
> === TPI ===
> TPI is an acronym for The Tor Project, Inc.
> 
> === tpo ===
> People on IRC often use `tpo` to abbreviate `torproject.org` when
> writing hostnames. For example, `trac.tpo` is an abbreviation for
> `trac.torproject.org`.

Hi Taylor, these look like good additions. Happy to add them, but I
don't actually know how to add new definitions on the navigation bar on
the right. Colin, could you add these or tell me how to?

Alison