Update content/server-server-api.md

Co-authored-by: Richard van der Hoff <[email protected]>

content/server-server-api.md

@@ -1256,7 +1256,7 @@ endpoint MUST be protected as follows:
     -   For [typing notifications (`m.typing`)](#typing-notifications), if
         the `origin` server is denied access to the room identified by
         `room_id`, the EDU MUST be ignored.
-    -   For [receipts (m.receipt)](#receipts), all receipts for a particular
+    -   For [receipts (`m.receipt`)](#receipts), all receipts for a particular
         room ID MUST be ignored if the `origin` server is denied access to
         the room identified by that ID.