Add a list of all existing concordance in wof:concordances property

[stepps00]

https://github.com/whosonfirst/whosonfirst-properties/tree/main/properties/wof#concordances

Related: https://github.com/whosonfirst-data/whosonfirst-data/issues/2006

It would be helpful to list out all of the existing keys WOF maintains in the wof:concordances property. Opening this issue to crawl all of the WOF repos to grab a list of existing concordances, and append it to the concordances README.

[thisisaaronland]

@stepps00 FYI:

https://github.com/whosonfirst/go-whosonfirst-concordances#wof-concordances-keys

Note the example that uses the go-whosonfirst-iterate-organization code to crawl all the WOF repos.