Updated docs for Connect: no need in NODE_ENV

raven-node documentation (https://github.com/mattrobenolt/raven-node) now says:

> We don't infer this from NODE_ENV automatically anymore. It's up to you to implement whatever logic you'd like.

Therefore sentry docs do not need to mention NODE_ENV configuration anymore.
Merge pull request #1102 from arty-name/patch-2

Updated docs for Connect: no need in NODE_ENV