Update basecamp.md to correct Redirect URI
Update basecamp.md to correct Redirect URI

Update basecamp.md to correct Redirect URI configuration. Previously we supplied 

 `${manage_url}.auth0.com/login/callback`

This string results in an incorrect Redirect URI that causes Basecamp connection configurations to error out when Try Connection is used, e.g., https://manage.auth0.com/dashboard/us/hackauth0n.auth0.com/login/callback in my case 

Changing this to match the Fitbit.md doc I found thus: 

 `${manage_url}.auth0.com/login/callback`

I believe fixes the problem and provides the correct Redirect URI of https://hackauth0n.auth0.com/login/callback
auth0/docs,auth0/docs,auth0/docs