Add more notes on migrating data from another installation

Related to #583 (Github Issue).

README.md

@@ -99,6 +99,8 @@ This is similar to the [EMnify/matrix-synapse-auto-deploy](https://github.com/EM
 
 - this one optionally **allows you to use an external PostgreSQL server** for Synapse's database (but defaults to running one in a container)
 
+- helps you **import data from a previous installation** (so you can migrate your manual virtualenv/Docker setup to a more managed one)
+
 
 ## Installation
 

docs/README.md

@@ -10,6 +10,14 @@
 
 - [Installing](installing.md)
 
+- **Importing data from another Synapse server installation**
+
+  - [Importing an existing SQLite database (from another installation)](importing-sqlite.md) (optional)
+
+  - [Importing an existing Postgres database (from another installation)](importing-postgres.md) (optional)
+
+  - [Importing `media_store` data files from an existing installation](importing-media-store.md) (optional)
+
 - [Registering users](registering-users.md)
 
 - [Updating users passwords](updating-users-passwords.md)