Modified docker documentation (#233)

Modified docker documentation

documentation/docs/install.md

@@ -70,7 +70,9 @@ Install `pg_tde` using one of available installation methods:
     docker run --name pg-tde -e POSTGRES_PASSWORD=mysecretpassword -d perconalab/pg_tde
     ```    
 
-    It builds and adds `pg_tde` extension to PostgreSQL 16. Relevant `postgresql.conf` and `tde_conf.json` are created in `/etc/postgresql/` inside the container. This directory is exposed as a volume.    
+    It builds and adds `pg_tde` extension to PostgreSQL 16. The `postgresql.conf` contains the required modifications. The `pg_tde` extension is added to `template1` so that all new databases automatically have the `pg_tde` extension loaded. 
+
+    Keys are not created automatically. You must configure a key provider and a principal key for each database  where you wish to use encrypted tables. See the instructions in the [Setup](setup.md) section, starting with the 4th point, as the first 3 steps are already completed in the Docker image.
 
     See [Docker Docs](https://hub.docker.com/_/postgres) on usage.    
 
@@ -82,4 +84,4 @@ Install `pg_tde` using one of available installation methods:
 
 ## Next steps
 
-[Setup](setup.md){.md-button}
+[Setup](setup.md){.md-button}