Trivial change to documentation. (#120)

Added section about correct & easy error reporting from parsing exceptions.

Author: kierun

docs/configobj.rst

@@ -1601,6 +1601,11 @@ code can be the same whether one error is raised in parsing , or several.
 It also means that in the most common case (a single error) a useful error
 message will be raised.
 
+Unless you want to format the error message differently from the default, you
+should use ``str(ex)`` or better yet, use the exception in a format where the
+conversion is implicit. This uses the exception's ``__str__()`` method which in all
+likelyhood will output all the information you want to know.
+
 .. note::
 
     One wrongly written line could break the basic structure of your config