* Add initial draft of a Perf Best Practices doc
Fixes aspnet/Docs##9526
* Minor proof-reading fixes
* rick's additions to Mike's perf doc
* rick's additions to Mike's perf doc
* work
* work
* work
* work
* work
* work
* work
* work
* react to EF feedback
* react to EF feedback
* react to MR feedback
* react to MR feedback