kgdb, docs: Fix <para> pdfdocs build errors

kgdb.pdf failed to build from 'make pdfdocs' giving errors such as:

jade:... Documentation/DocBook/kgdb.xml:200:8:E:
document type does not allow element "para" here; missing one of
"footnote", "caution", "important", "note", "tip", "warning",
"blockquote", "informalexample" start-tag

Fixing minor <para> and <sect> issues allows kgdb.pdf to be generated
under Fedora20.

Originally submitted by rajaneesh.acharya@yahoo.com in 2011, discussed here:
http://permalink.gmane.org/gmane.linux.documentation/3954


as patch:
 The following are the enhancements that removed the errors
 while issuing "make pdfdocs"

[graham.whaley@intel.com: Improved commit message and ported to 3.18.1]
Signed-off-by: Graham Whaley <graham.whaley@intel.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>