Documentation updates for interactive sessions

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/swagger.yaml

@@ -8508,6 +8508,9 @@ paths:
       description: |
         Start a new interactive session with a server. Session allows server to call back to the client for advanced capabilities.
 
+        > **Note**: This endpoint is *experimental* and only available if the daemon is started with experimental
+        > features enabled. The specifications for this endpoint may still change in a future version of the API.
+
         ### Hijacking
 
         This endpoint hijacks the HTTP connection to HTTP2 transport that allows the client to expose gPRC services on that connection.
@@ -8541,4 +8544,4 @@ paths:
           description: "server error"
           schema:
             $ref: "#/definitions/ErrorResponse"
-      tags: ["Session"]
+      tags: ["Session (experimental)"]

docs/api/version-history.md

@@ -22,6 +22,9 @@ keywords: "API, Docker, rcli, REST, documentation"
 * `POST /secrets/(name)/update` now returns status code 400 instead of 500 when updating a secret's content which is not the labels.
 * `POST /nodes/(name)/update` now returns status code 400 instead of 500 when demoting last node fails.
 * `GET /networks/(id or name)` now takes an optional query parameter `scope` that will filter the network based on the scope (`local`, `swarm`, or `global`).
+* `POST /session` is a new endpoint that can be used for running interactive long-running protocols between client and
+  the daemon. This endpoint is experimental and only available if the daemon is started with experimental features
+  enabled.
 
 ## v1.30 API changes