fix Group Example
Changing extension key type from IRL to IRI.
Merge pull request #351 from jloic/master

Appendix D example typo
Clarifying as extension key.
Merge pull request #350 from andyjohnson/master

Updated Appendix A
Merge pull request #352 from dnjohnson/extensions-fix

Changing extension key type from IRL to IRI.
Merge pull request #25 from adlnet/master

Sync up!