Fix typo (successfuly)

Author: lcrilly

frontend.conf

@@ -58,7 +58,7 @@ server {
         # Absent/invalid OpenID Connect token will (re)start auth process (including refresh)
         error_page 401 = @oidc_auth;
 
-        # Successfuly authenticated users are proxied to the backend,
+        # Successfully authenticated users are proxied to the backend,
         # with 'sub' claim passed as HTTP header
         proxy_set_header username $jwt_claim_sub;
         proxy_pass http://my_backend; # The backend site/app