#982 Add community page to ESCET website

• Best to review per commit.
• I've started with TNO-ESI and TU/e as members. I assume these are OK to add, since these organizations are already officially involved, through committers / project leads. @ahofkamp/@bvanbeek/@mgoorden7u4: can one of you confirm, for TU/e?
• I'll contact other organizations to see if we can also list them.
• There will be more content on the community page later. This is only the first step.
• I opted for a new community folder to put the community page, as I expect it to get more pages later.

Addresses #982