docs: describe the bundled renderer service

.env.example

@@ -38,12 +38,13 @@ STICKER_PACK_NAME=miti99_by_miti99bot
 # Without it every /lol* fetch fails; the stale cache covers ≤60 min.
 LOL_PANDASCORE_TOKEN=
 
-# Optional /wheelofnames GIF and /gacha MP4 renderer. Standard deployment:
-# https://github.com/tiennm99/wheelofnames. Set the full /api/gif endpoint;
-# /gacha calls /api/gacha on the same service. Leave blank to fall back to text
-# selection.
+# Optional /wheelofnames GIF and /gacha MP4 renderer: the renderer/ service in
+# this repository. compose.yml fixes this to http://renderer:3000/api/gif, so
+# set it only when running the bot outside compose. /gacha calls /api/gacha on
+# the same service. Leave blank to fall back to text selection.
 WHEELOFNAMES_API_URL=
-# Bearer token matching the wheelofnames service API_TOKEN when URL is set.
+# Bearer token shared with the renderer; compose passes it to the renderer as
+# API_TOKEN. Required for the renderer to start.
 WHEELOFNAMES_API_TOKEN=
 
 # ====================== Leave UNSET on self-host ==================