MSSQL: How to document stored procedures without auto-documenter?

MSSQL: How to document stored procedures without auto-documenter?

There has been a few questions on SO about how to's and best practices of
documenting stored procedures in Microsoft SQL Server. However, most of
them relate to auto-documenting tools and using third-party services in
order to do so.
Intent
I have a online wiki that's attached to my software versioning and bug
tracking software (JIRA). They link together both in task/issues and the
wiki (really beneficial to us overall). Now I want to start going through
about a hundred stored procedures and start documenting them in our online
wiki.
Question
How do you document procedures through external documentation without
simply copying over the code and without using auto-documenting tools?
What information about the procedure at the core level should I provide in
that documentation? For example, the parameters, columns and joins it
executes on top of it's intent? Or the bare minimum of just the intent?
Clarity Details
I know this may be broad, but I'm not looking for the best practice. I'm
looking for a good method to build into a best practice. Something that
any DBA could read and know exactly what is going on in that procedure as
well enough detail to trigger someone to find what they are looking for
during tasks.