Add example rule for using imported payee contains (#293)

The question of not having contains under payee in rules gets asked a
lot. I added an example for it.

I also changed the name of that page to "Rules Examples" to be more
clear on what it is.

docs/budgeting/rules/custom.md

@@ -1,7 +1,13 @@
-# Supercharge your Budget
+# Rules Examples
 
 This page has examples of custom rules that some of our users have found useful for their own budgets. If you have any custom rules you're proud of, click the “Edit this page” button below to propose adding them to this page [tell us about them](/contact)!
 
+### Q: How do I set the payee when the payee name changes between transactions
+
+**A:** Sometimes the payee shows up slightly differently from transaction to transaction.  To set the same payee every time and not create a new one every time a new transaction is imported, use a **Pre** rule that reads the imported payee field and finds the merchant name using a "contains" condition.
+
+![](/img/rules-custom/custom-rules-imported-payee.png)
+
 ### Q: How do I set a default account when I add transactions?
 
 **A:** Set a **Pre** rule to check for an empty account field. When entering a transaction in the "All Accounts" ledger or from the ledger of a Category listing, your preferred default account will be auto filled.