feat: unable to login troubleshooting tips

content/docs/help/troubleshooting.md

@@ -9,8 +9,18 @@ images: []
 menu:
   docs:
     parent: "Help"
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+weight: 541
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 ---
 
-Coming soon
+## Q: I just setup an instance but I am unable to login
+
+mCaptcha by default is configured to server at `localhost` hostname. If
+the instance is deployed at another hostname, please try setting
+`MCAPTCHA_SERVER_DOMAIN` environment variable to the hostname at which
+your instance is deployed or setting the equivalent in config.toml:
+
+```toml
+[server]
+domain=mydomain
+```