I am going to be writing some user-facing documentation for a database that visitors can query. That is, the people writing queries are not the ones who created the database; they can come in, look at what the database offers, and write their SQL queries. Think of something like SEDE.
I could just give people the database schema, but that only tells you so much. For example, if a value is an integer but it's an enumeration (1 means this, 2 means that, 3 means this other thing, etc), you can't get that from the schema alone. So I need to produce some documentation for the tables and columns in the database, which also provides me the opportunity to present the information in whatever organizational structure makes the most sense for our users.
My question is: are there best practices for going from a DB schema to documentation? If this were an API, for example, then in some languages I could write inline comments that could be automatically turned into reference documentation using tools like Javadoc or Doxygen. Is there something like that for DB schemas, or would I have to write my own transformation tools (which isn't worth the effort for the size of this project)? Or do people writing schemas just inspect the schema and write separate documentation? Are there conventions for doing this? I'm an experienced technical writer but I'm new to databases.
(In case it matters, I need to deliver HTML. This is a volunteer project (not actually open-source, but along those lines) and I have no budget for tools.)