Fix names waterschappen

[joepio]

Some of the Waterschappen (de dommel & aa en maas) do not have "Waterschap" in their names. Not sure how this happens.

@breyten

[robvandijk]

A call to https://rest-api.allmanak.nl/v1/overheidsorganisatie?systemid=eq.21099 returns the following:
naam "Aa en Maas"
and this is what is being used. So if we want the names to include Waterschap we'll need to include it ourselves.

[vanderburgt]

Can't we just use the types property to add the prefix 'waterschap' in the frontend?