MultiDB README: Add a bit more detail

diff --git a/alembic/templates/multidb/README b/alembic/templates/multidb/README
index 5db219f9d2c08d9197977985c57764a38fa0d918..f046ec91427e2f4edd53dcb5409b21955c8fd0af 100644 (file)
--- a/alembic/templates/multidb/README
+++ b/alembic/templates/multidb/README
@@ -1 +1,12 @@
-Rudimentary multi-database configuration.
\ No newline at end of file
+Rudimentary multi-database configuration.
+
+Multi-DB isn't vastly different from generic. The primary difference is that it
+will run the migrations N times (depending on how many databases you have
+configured), providing one engine name and associated context for each run.
+
+That engine name will then allow the migration to restrict what runs within it to
+just the appropriate migrations for that engine. You can see this behavior within
+the mako template.
+
+In the provided configuration, you'll need to have `databases` provided in
+alembic's config, and an `sqlalchemy.url` provided for each engine name.