Add links to other RSE communities chats (outside nordics)

[avancra]

The idea is that if someone joins N-RSE but is interested into a wider network (e.g. DE RSE, UK RSE, and others), N-RSE website would provide the links to those communities, not only websites, but also chat or slack, etc.

[bast]

Great idea!

[samumantha]

Also add: http://researchsoftware.org/