Improve "Typing Notifications" section of the CS API (#2375)

* Convert m.typing JSON schema to YAML

For consistency with other schemas.

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

* Clarify string formats in Typing Notifications section of the CS API

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

* Add changelog

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

---------

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

changelogs/client_server/newsfragments/2375.clarification

@@ -0,0 +1 @@
+Clarify formats of string types.

data/api/client-server/typing.yaml

@@ -36,6 +36,8 @@ paths:
           example: "@alice:example.com"
           schema:
             type: string
+            format: mx-user-id
+            pattern: "^@"
         - in: path
           name: roomId
           description: The room in which the user is typing.
@@ -43,6 +45,8 @@ paths:
           example: "!wefh3sfukhs:example.com"
           schema:
             type: string
+            format: mx-room-id
+            pattern: "^!"
       requestBody:
         content:
           application/json:

data/event-schemas/schema/m.typing.yaml

@@ -1,29 +1,27 @@
-{
-    "$schema": "https://json-schema.org/draft/2020-12/schema",
-    "type": "object",
-    "title": "Typing Event",
-    "description": "Informs the client of the list of users currently typing.",
-    "allOf": [{
-        "$ref": "core-event-schema/event.yaml"
-    }],
-    "properties": {
-        "content": {
-            "type": "object",
-            "properties": {
-                "user_ids": {
-                    "type": "array",
-                    "items": {
-                        "type": "string"
-                    },
-                    "description": "The list of user IDs typing in this room, if any."
-                }
-            },
-            "required": ["user_ids"]
-        },
-        "type": {
-            "type": "string",
-            "enum": ["m.typing"]
-        }
-    },
-    "required": ["type", "content"]
-}
+$schema: https://json-schema.org/draft/2020-12/schema
+
+type: object
+title: Typing Event
+description: Informs the client of the list of users currently typing.
+allOf:
+- $ref: core-event-schema/event.yaml
+properties:
+  content:
+    type: object
+    properties:
+      user_ids:
+        type: array
+        items:
+          type: string
+          format: mx-user-id
+          pattern: "^@"
+        description: The list of user IDs typing in this room, if any.
+    required:
+    - user_ids
+  type:
+    type: string
+    enum:
+    - m.typing
+required:
+- type
+- content