docs: HAProxy documentation warning format (#2054)

Updated warning message for HAProxy documentation. And fixed a typo

Author: fallenbagel

docs/extending-jellyseerr/reverse-proxy.mdx

@@ -269,7 +269,9 @@ Add the following Location block to your existing Server configuration.
 
 ## HAProxy (v3)
 
-    This is third-party documentation maintained by the community. We can't provide support for this setup and are unable to test it.
+:::warning
+This is a third-party documentation maintained by the community. We can't provide support for this setup and are unable to test it.
+:::
 
     Add the following frontend and backend configurations for your seerr instance:
     ```haproxy