Added documentation (if a bit minimal) on customizing reports in 1.4

[Chris Travers <..hidden..>]

For those interested in review, please wget
https://ledger-smb.svn.sourceforge.net/svnroot/ledger-smb/trunk/doc/LedgerSMB-manual.pdf
if you haven't checked out trunk.  The documentation goes from the
lower part of page 64 to the bottom of page 68.

I would be interested in getting feedback through helping write
reports for 1.4.  If you are interested in helping out (and learning
how to write reports on 1.4) please let me know.

Best Wishes,
Chris Travers