tck/README.md refers to annotation style @Optional test markers, which we removed

tck/README.md needs to be refreshed before we cut an 1.0, it refers to outdated styles of optional test marking. @purplefox also had a few more points where things were confusing in the README in his recent issues.

I'll update the readme (note to self: include information about the new `triggerRequest()` method which we may have to introduce)
