Add link to BRP

content/news/2019-briar-1.2-released-remote-contacts.md

@@ -30,6 +30,9 @@ The onion service is only used to add this one single contact
 by exchanging cryptographic keys and other information.
 It will be discarded once the contact was added.
 
+Technical details can be found in the documentation of the
+[Bramble Rendezvous Protocol](https://code.briarproject.org/briar/briar-spec/blob/master/protocols/BRP.md).
+
 As with all other apps, when adding contacts remotely, there is the possibility
 that a [man-in-the-middle attack](https://en.wikipedia.org/wiki/Man-in-the-middle_attack)
 compromises the contact relationship.