chore: Update admin command docs

docs/reference/admin/debug.md

@@ -10,7 +10,13 @@ Echo input of admin command
 
 ## `!admin debug get-auth-chain`
 
-Get the auth_chain of a PDU
+Loads the auth_chain of a PDU, reporting how long it took
+
+## `!admin debug show-auth-chain`
+
+Walks & displays the auth_chain of a PDU in a mermaid graph format.
+
+This is useless to basically anyone but developers, and is also probably slow and memory hungry.
 
 ## `!admin debug parse-pdu`
 
@@ -44,6 +50,12 @@ This is functionally equivalent to `GET /_matrix/client/v3/rooms/{roomid}/state`
 
 Of course the check is still done on the actual client API.
 
+## `!admin debug get-state-at`
+
+Gets all the room state events at the specified event.
+
+State at event might not be available for some PDUs, such as rejected ones.
+
 ## `!admin debug get-signing-keys`
 
 Get and display signing keys from local cache or remote server