Add some procedural preamble to Encrypted forms and follow list style

encrypted-forms.rst

This page is good, but it contains a series of sub-procedures within the main procedure. It would be more clear if there was a summary of the main procedure near the top. Also, needs to use OL procedure style.

Part of #402

Start with encrypted-forms.rst and review its current procedure structure. Add a short summary of the main procedure near the top and update the procedure to use OL procedure style; confirm the documentation still builds successfully with Sphinx.

Written by the indexing model from the issue text.