docs/ap_extensions.md: Add JSON-LD full names

docs/ap_extensions.md

@@ -3,8 +3,8 @@
 
 The following endpoints are additionally present into our actors.
 
-- `oauthRegistrationEndpoint`
-- `uploadMedia`
+- `oauthRegistrationEndpoint` (`http://litepub.social/ns#oauthRegistrationEndpoint`)
+- `uploadMedia` (`https://www.w3.org/ns/activitystreams#uploadMedia`)
 
 ### oauthRegistrationEndpoint
 
@@ -14,7 +14,7 @@ See <https://docs.joinmastodon.org/methods/apps/>
 
 ### uploadMedia
 
-Inspired by <https://www.w3.org/wiki/SocialCG/ActivityPub/MediaUpload>
+Inspired by <https://www.w3.org/wiki/SocialCG/ActivityPub/MediaUpload>, it is part of the ActivityStreams namespace because it used to be part of the ActivityPub specification and got removed from it.
 
 Content-Type: multipart/form-data
 
@@ -28,12 +28,14 @@ The object given in the reponse should then be inserted into an Object's `attach
 
 ## ChatMessages
 
-ChatMessages are the messages sent in 1-on-1 chats. They are similar to
+`ChatMessage`s are the messages sent in 1-on-1 chats. They are similar to
 `Note`s, but the addresing is done by having a single AP actor in the `to`
 field. Addressing multiple actors is not allowed. These messages are always
 private, there is no public version of them. They are created with a `Create`
 activity.
 
+They are part of the `litepub` namespace as `http://litepub.social/ns#ChatMessage`.
+
 Example:
 
 ```json