Add "links" section to v14 schema

[dbrgn]

In order to cover some use cases that we haven't yet anticipated, it would be great to have a generic "links" section in the schema (as already suggested by @rnestler in #30).

Suggestion:

{
  …
  "links": [
    {
      "name": "Door Twitter",
      "description": "The Twitter account which tweets our door open status",
      "url": "https://twitter.com/foo/bar"
    },
    {
      "name": "Jitsi",
      "description": "Our Jitsi instance, public for everybody!",
      "url": "https://jitsi.example.org/"
    }
  ]
}

The name and url fields would be required, description is optional.

[dbrgn]

I wonder if links should also have a type field. It would be optional and free-form, but we could specify a few suggestions, like forum, chat, etc. That would allow us to find certain types of links across all spaces.

What do you think, @gidsi @rnestler @s3lph

[rnestler]

I wonder if links should also have a type field. It would be optional and free-form, but we could specify a few suggestions, like forum, chat, etc. That would allow us to find certain types of links across all spaces.

If it is free form, maybe allow a set of tags? Like tags: ["twitter", "social-media", "contact"]?

[s3lph]

I think such a type field, and especially suggested values/tags is kinda contradictory to use cases that we haven't yet anticipated; IMO a link and human-readable name/description is sufficient.

[rnestler]

Tags could have the advantage, that we could see which tags people use most often for their stuff and gain some insight which things may be standardized further.

[dbrgn]

Ok, let's merge this without tags for now. We can always add them later.

I forgot to add it to the changelog though... :facepalm: