Add GET to /api/v1/pleroma/flavour/:flavour

Related to: https://git.pleroma.social/pleroma/mastofe/issues/65

docs/api/pleroma_api.md

@@ -118,7 +118,7 @@ Request parameters can be passed via [query strings](https://en.wikipedia.org/wi
 See [Admin-API](Admin-API.md)
 
 ## `/api/v1/pleroma/flavour/:flavour`
-* Method `POST`
+* Method `POST`, `GET`
 * Authentication: required
 * Response: JSON string. Returns the user flavour or the default one on success, otherwise returns `{"error": "error_msg"}`
 * Example response: "glitch"

lib/pleroma/web/router.ex

@@ -318,6 +318,7 @@ defmodule Pleroma.Web.Router do
       delete("/filters/:id", MastodonAPIController, :delete_filter)
 
       post("/pleroma/flavour/:flavour", MastodonAPIController, :set_flavour)
+      get("/pleroma/flavour/:flavour", MastodonAPIController, :set_flavour)
 
       post("/reports", MastodonAPIController, :reports)
     end