[talk-au] NSW GNB licensing

[Andrew Harvey]

Historically Geographical Name Register of NSW data[1] has been used
(and is still present) in OSM [2][3].

Based on the latest advice from the OSMF regarding CC BY 4.0[4] content
and OSM, the GNB of NSW has completed the waiver form uploaded to
https://wiki.openstreetmap.org/wiki/File:NSW_GNB_170427_OpenStreetMap.pdf.
This should clear up any open licensing issues.

As such I've added the attribution requested from
http://www.gnb.nsw.gov.au/copyright in the OSM wiki at
https://wiki.openstreetmap.org/wiki/Contributors#Geographical_Name_Register_.28GNR.29_of_NSW

[1] http://www.gnb.nsw.gov.au/place_naming/placename_search
[2]
https://lists.openstreetmap.org/pipermail/legal-talk/2007-July/thread.html#385
[3]
https://lists.openstreetmap.org/pipermail/talk-au/2016-April/thread.html#10905
[4] https://blog.openstreetmap.org/2017/03/17/use-of-cc-by-data/