Changes for ability to write to other databases.

README.md

@@ -40,6 +40,28 @@ To get JSON in the form to use with jTables, do:
 
     curl localhost:8080/?handd=true
 
+## Databases
+The default database is SQLite and requires no configuration. The tables
+are written into the default ("main.db") database.
+
+If you'd like to use a different database, there are some environment
+variables that need setting.
+
+HPOTTER\_DB -- the name of the database type, e.g.: "mysql".
+    Defaults to "sqlite".
+
+HPOTTER\_DB\_PASSWORD -- e.g.: "my-secret-pw".
+    Defaults to "".
+
+HPOTTER\_DB\_HOST
+    Defaults to "127.0.0.1".
+
+HPOTTER\_DB\_PORT -- e.g.: 3306
+    Defaults to "".
+
+HPOTTER\_DB\_DB -- The database where the tables are placed e.g.: hpotter.
+Created if not present.  Defaults to "hpotter".
+
 ## Directory structure
 hpotter/