Mynewt ranging profile: DS-TWR /w extended data payload

We are interested in having some data also be exchanged during ranging events and looking at the mynewt github repo it seems like this has already been implemented as a ranging profile.

Unfortunately there seems to be no documentation or examples on the following profile “twr_ds_ext”. All I can find is that it stands for “DS-TWR /w extended data payload”. How do I use it? What is the extended data payload? Can I customize the payload? Where can I access the payload? etc.

Also is there a better place to ask Mynewt core questions? There seems to be a Slack channel but I am unable to access it.