[development] Help add descriptions to the schema table definitions

schema.module now supports displaying documentation included in the schema data structure as specified in http://drupal.org/node/146939. We should add this information for all core tables. There are 64 such tables so if a handful of developers document the tables they are most familiar with it will all get done very quickly. So, please choose a core module or two and document its tables. To avoid having many people trying to edit the same patch file, add your docs to the issue: http://drupal.org/node/160599. I will combine all responses into a single patch. The patch will change the .schema files but only by adding documentation so I assume this will be acceptable even in code freeze. Thanks, Barry