Changed some ReST formatting of headers (in forms/validation.txt).

.. _described later:

Form subclasses and modifying field errors

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Sometimes, in a form's ``clean()`` method, you will want to add an error

message to a particular field in the form. This won't always be appropriate

    explanation makes you feel more comfortable. The result is the same.

Using validation in practice

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The previous sections explained how validation works in general for forms.

Since it can sometimes be easier to put things into place by seeing each