[wolf4ood]

What this PR changes/adds

Adds a "Database Schemas" page to the adopter documentation (Distributions, Deployment, and Operations):

• where the SQL schemas come from (the store modules' *-schema.sql, BOMs, datasources);
• what edc.sql.schema.autocreate does and doesn't do: it creates missing tables and indexes, it never changes
  existing tables, and it isn't a migration tool;
• production setup: apply the schemas with a DDL user, run the runtime with a DML-only user, manage changes with a migration tool;
• why schema changes must not run from replicas that serve traffic;

Why it does that

The documentation didn't say how the schema is meant to be created or upgraded.

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method
signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Who will sponsor this feature?

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Linked Issue(s)

Closes # <-- insert Issue number if one exists

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