Update apple-app-site-association

[noumantahir]

To allow auto login and referral signup in mobile app specifically iOS we need to allow url path /login and /signup

We can also add path /purchase if for some reason user scan QR to purchase points either while not having app installed or using default iOS camera for scanning, it will install app and directly open purchase points screen. It may be an edge case though

https://www.ecency.com/apple-app-site-association