UnitTestFrameworkPkg/Readme.md: Update documentation for latest features
* Add additional documentation about running tests locally
* Add a note about XML formatting
* Update readme with BaseLib and UNIT_TESTING_DEBUG
Cc: Michael D Kinney <michael.d.kinney@intel.com> Cc: Sean Brogan <sean.brogan@microsoft.com> Signed-off-by: Bret Barkelew <Bret.Barkelew@microsoft.com> Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com> Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>