apidocs: Fix playground URLs and operationIDs.

We standardized on "Code playground" for this feature, so use that
in the URLs and API documentation.

templates/zerver/api/changelog.md

@@ -162,14 +162,14 @@ field with an integer field `invite_to_realm_policy`.
 
 **Feature level 49**
 
-* Added new [`POST /realm/playground`](/api/add-playground) and
-  [`DELETE /realm/playground/{playground_id}`](/api/remove-playground)
-  endpoints for realm playgrounds.
+* Added new [`POST /realm/playground`](/api/add-code-playground) and
+  [`DELETE /realm/playground/{playground_id}`](/api/remove-code-playground)
+  endpoints for code playgrounds.
 * [`GET /events`](/api/get-events): A new `realm_playgrounds` events
-  is sent when changes are made to a set of configured playgrounds for
+  is sent when changes are made to a set of configured code playgrounds for
   an organization.
 * [`POST /register`](/api/register-queue): Added a new `realm_playgrounds`
-  field, which is required to fetch the set of configured playgrounds for
+  field, which is required to fetch the set of configured code playgrounds for
   an organization.
 
 **Feature level 48**

templates/zerver/help/include/rest-endpoints.md

@@ -61,8 +61,8 @@
 * [Add a linkifier](/api/add-linkifier)
 * [Update a linkifier](/api/update-linkifier)
 * [Remove a linkifier](/api/remove-linkifier)
-* [Add a playground](/api/add-playground)
-* [Remove a playground](/api/remove-playground)
+* [Add a code playground](/api/add-code-playground)
+* [Remove a code playground](/api/remove-code-playground)
 * [Get all custom emoji](/api/get-custom-emoji)
 * [Upload custom emoji](/api/upload-custom-emoji)
 * [Get all custom profile fields](/api/get-custom-profile-fields)

zerver/openapi/zulip.yaml

@@ -6989,7 +6989,7 @@ paths:
                 $ref: "#/components/schemas/JsonSuccess"
   /realm/playgrounds:
     post:
-      operationId: add_realm_playground
+      operationId: add_code_playground
       tags: ["server_and_organizations"]
       description: |
         Configure [code playgrounds](/help/code-blocks#code-playgrounds) for the organization.
@@ -7045,7 +7045,7 @@ paths:
                     example: {"id": 1, "result": "success", "msg": ""}
   /realm/playgrounds/{playground_id}:
     delete:
-      operationId: remove_realm_playground
+      operationId: remove_code_playground
       tags: ["server_and_organizations"]
       description: |
         Remove a [code playground](/help/code-blocks#code-playgrounds) previously