Add internal hyperlink

proposals/3886-simple-rendezvous-capability.md

@@ -16,8 +16,8 @@ information such as:
 To enable [MSC3906](https://github.com/matrix-org/matrix-spec-proposals/pull/3906) and support any future proposals this MSC proposes a simple HTTP based protocol that can be used to
 establish a direct communication channel between two IP connected devices.
 
-This channel SHOULD be considered untrusted by both devices, and SHOULD NOT be
-used to transmit sensitive data in plaintext.
+This channel [SHOULD be considered untrusted](#confidentiality-of-data)
+by both devices, and SHOULD NOT be used to transmit sensitive data in plaintext.
 
 It will work with devices behind NAT. It doesn't require homeserver administrators to deploy a separate server.