Support alerts (notes, warnings, rationales)

content/rooms/v3.md

@@ -22,21 +22,20 @@ and the potentially problematic slash).
 
 ## Server implementation components
 
-Warning
-
+{{% boxes/warning %}}
 The information contained in this section is strictly for server
 implementors. Applications which use the Client-Server API are generally
 unaffected by the intricacies contained here. The section above
 regarding client considerations is the resource that Client-Server API
 use cases should reference.
+{{% /boxes/warning %}}
 
 Room version 3 uses the state resolution algorithm defined in [room
 version 2](v2.html), and the event format defined here.
 
 ### Event IDs
 
-Rationale
-
+{{% boxes/rationale %}}
 In other room versions (namely version 1 and 2) the event ID is a
 distinct field from the remainder of the event, which must be tracked as
 such. This leads to complications where servers receive multiple events
@@ -44,6 +43,7 @@ with the same ID in either the same or different rooms where the server
 cannot easily keep track of which event it should be using. By removing
 the use of a dedicated event ID, servers are required to track the
 hashes on an event to determine its ID.
+{{% /boxes/rationale %}}
 
 The event ID is the [reference
 hash](../server_server/%SERVER_RELEASE_LABEL%.html#reference-hashes) of