Build the site from a make file.
Then you establish a single authoritative source of information on all you versions and patches.
Building the site this way, also makes applying the right patches the default action. If you rely on others to read your documentation, you will definitely have people failing this. Drush make however will always apply the patch, unless told otherwise.
Make files can also have comments, meaning there's a natural place to document why the patch is there. This comment should ideally include a a link to a d.o issue.