Extend /listings endpoint

PROTOCOL.md

@@ -101,13 +101,34 @@ See <https://github.com/oxen-io/session-pysogs/blob/dev/sogs/routes/onion_reques
 
 ### GET `/listings`
 
-Description: Enumerate the identifiers of the listings hosted by the listing provider.
+Description: Enumerate the listings hosted by the listing provider with listing-specific details.
 
 Example response:
 
 ```json
 {
-    listings: ["tech", "languages", "privsec", "casual", "nsfw", "all"]
+    listings: {
+      "tech": {
+          name: "Tech Communities",
+          communities: 5
+      },
+      "privsec": {
+          name: "Privacy & Security",
+          communities: 4
+      },
+      "casual": {
+          name: "Casual Communities",
+          communities: 3
+      },
+      "nsfw": {
+          name: "18+ Communities",
+          communities: 3
+      }
+      "all": {
+          name: "All Communities",
+          communities: 10
+      }
+    }
 }
 ```