docs(guide/Running in Production): ng-strict-di

Adding note about Strict DI mode.
this isn't necessarily something we'd recommend, because these tools just don't do a very good job.

Also, I'd be questionable about the "performance benefit", we've never measured a performance benefit and that was never the intent of strict-DI --- it's really a debugging tool, that's about it. The main benefit of using it in production is so that you can be sure your minified scripts won't be broken terribly.