Re: [dita-comment] Issues with DITA 1.2 CD03: Obsolete file and brokencross-references

>From the attached report, it looks like we need to fix <xref>s in the
following topics:
- p. 17 and 18 "2.1.1.2 DITA terminology and notation" 
- p.  24 "2.1.2.1.2.1 Disciplined, topic-oriented writing"
- p. 52 "2.1.3.3 DITA linking"
- p. 1203 "Appendix B.1.1 Changes from DITA 1.1 to DITA 1.2" 

We might also want to delete the keyref.dita file so that people don't
accidentally link to it in future.