Add sentry to docs app

[asvae]

This might not look like a priority, or a big thing, but it is:

• easy to do,
• helps with debug,
• gives sentry experience which you can exploit on projects 😉.

• We want to have global error handling.
• Make sure it's only enabled on production and staging. There should be absolutely no sentry for local server.
• Add optional flag to force enable sentry.