docs: explain the P2P diagnostic workflow

Guide users through Diagnostic summary, Diag logging, transfer progress,
symptom checks, and evidence collection from both devices. Link the guide
from the P2P, troubleshooting, reporting, and documentation entry points.
Keep transport compatibility and observation limits explicit.

Validated with the troubleshooting documentation Inspector, 145 local
references, 34 heading anchors, and current English UI labels. Runtime
source and translations are unchanged.

docs/p2p.md

@@ -2,11 +2,11 @@
 
 Peer-to-peer (P2P) synchronisation transfers Vault data between LiveSync devices through WebRTC. It does not require a central database containing a copy of the Vault. It does require a signalling relay so that devices can discover one another and establish a connection.
 
-For the procedure for the first and additional devices, see [Set up peer-to-peer synchronisation](setup_p2p.md). For connection problems, see [Peer-to-Peer Synchronisation Tips](tips/p2p-sync-tips.md).
+For the procedure for the first and additional devices, see [Set up peer-to-peer synchronisation](setup_p2p.md). For connection problems, see [Peer-to-Peer Synchronisation Tips](tips/p2p-sync-tips.md). Use the [P2P diagnostic guide](tips/p2p-diagnostics.md) to investigate discovery and transfer problems with the summary, logs, and progress indicators.
 
 ## Updating a P2P group
 
-The unreleased transport update uses Trystero 0.26.0, whose data format is
+The Trystero 0.26.0 transport uses a data format which is
 incompatible with the previous transport. Update every device in the P2P
 group, including CLI and WebPeer clients, before resuming P2P synchronisation.
 Keeping the same Group ID, passphrase, and relay settings does not make mixed