Summary:
We migrated everyone on Product Pains over to our new service, Canny. We also moved every product's feedback to a product-specific subdomain (eg. https://react-native.canny.io/feature-requests).
This PR updates every Product Pains URL over to its new Canny version.
Changes only affect docs, blog posts, and bot responses - not the React Native library itself.
**Test plan**
I visited https://react-native.canny.io/feature-requests. Since there are no code changes this seems sufficient but let me know if I need to run the blog website or something.
Closes https://github.com/facebook/react-native/pull/12429
Differential Revision: D4581492
Pulled By: hramos
fbshipit-source-id: 7d124ab7ed9228d47f1bc4417d8992f15ff17f01