add intro paragraph

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@2208 57a11ea4-9604-0410-9ed3-97b8803252fd

doc/html/C/xacc-apar.html

@@ -12,8 +12,15 @@
     <h1>Accounts Payable and Accounts Receivable</h1>
 
     <p> A/R (Accounts Receivable) and A/P (Accounts Payable) are
-    somewhat deep, and require thought to fully understand
-    them.</p>
+advanced concepts that are used by businesses to record sales for which
+they are not paid right away, or to record bills that they've received,
+but might not pay until a little while later.  These types of accounts
+primarily when you've got a lot of bills and receipts flowing in and
+out, and don't want to loose track of them just because you don't
+pay/get paid right away.   For almost all home users, A/R and A/P
+are too complicated and confusing to be worth the effort.
+
+    </p>
 
     <h1> Accounts Receivable</h1>