add login error (home-assistant#60)

add login error

docs/misc/errors.md

@@ -3,3 +3,9 @@ title: Errors
 ---
 
 Here's a list of all the error codes you may experience with further documentation about why this happens and what to do about it.
+
+# Setup and Connectivity
+
+## "Invalid Client ID or Redirect URI"  or  "OS Error while looking up redirect_uri"
+Check your `home-assistant.log` file for any errors about `indieauth`. If it also mentions a OS Error, you most likely have a broken IPv6 implementation. You can confirm this by running `curl -v6 https://home-assistant.io/iOS/beta-auth` from the machine you run Home Assistant on. If you receive a error about not being able to connect to the server, your IPv6 stack is broken and you should disable it.
+