Hi and welcome at the new community portal,
quoting there from the last announcement related to the closing of the ML:
this is a reminder:
Only 9 days to go until this mailing list is shut down.
The community forum is already very active.
Lets meet there! :
so you already have found the new home of discussions around VT development.
Just to summarize:
http://www.openvas.org/writing-nvts.html is deprecated and probably will be removed soon. New content will be maintained in VT Development and probably split into separate topics at some point in the future.
If you have plugin/VT specific questions related to development, VT requests or false positive/false negative reports you can use the following category: https://community.greenbone.net/c/vulnerability-tests
If you have issues with the Feed (e.g. slow sync, no sync at all or similar) you can use the following category: https://community.greenbone.net/c/feed-services
And finally when having question on how plugins/VTs are used (e.g. how the scanner is starting them) you can use the following category: https://community.greenbone.net/c/gse
Hope this gives a brief overview over the new communication channel here.