Update the hacking.html location in misc-docs.
Update the hacking.html location in misc-docs.

* doc/misc-docs/best_practices.xml
  (misc-docs-best_practices-sect-1, misc-docs-best_practices-sect-2): 
    Update links to the hacking.html file and add missing <filename/> 
    elements.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion