Add healthcheck endpoint

src/handlers/mod.rs

@@ -31,6 +31,9 @@ async fn docs() -> &'static str {
 
         The current endpoints are:
 
+            GET /healthcheck
+                Returns OK when the API is running.
+
             GET /v1/profile
                 Return's the user's profile (username, name, avatar, banner, and URL).
 
@@ -113,3 +116,7 @@ async fn docs() -> &'static str {
         "
     )
 }
+
+async fn healthcheck() -> &'static str {
+    "OK"
+}