Add link to related effort at OSDC-Code-Maven/open-source-by-organizations

[pdurbin]

I just discovered a related effort and created a pull request to add @IQSS to the list:

• add IQSS at Harvard OSDC-Code-Maven/open-source-by-organizations#69

We should probably link to this project from our README since it's so highly related.

[pdurbin]

Not only did @szabgab from @OSDC-Code-Maven merge that pull request, he hooked us up with a chat room! See this issue:

• new chat room on Zulip for Open Source at Harvard! #41

I still need to update the README. It's a bit of a mess. 😅