Fix GeoJSON to Geometry node description

[koettert]

Node description states that the field “geojson column” expects a GeoJSON column to convert. However, it does not recognize any JSON column but only STRING columns.

The input port description lacks in detail, as it states “input table to extract the geometry column from”. Actually, the geometry column is what we want to generate, so why should our input table have it already?

The embedded “From GeoJSON” link actually points to the from_wkt method.