Revised Docker.md (#1311)

Docker.md

@@ -1,24 +1,27 @@
 ### Run Minio docker image
 
-Start docker with random keys, generated name, and ephemeral data:
-
+## Test Minio Docker Container
+Minio generates new access and secret keys each time you run this command. Container state is lost after you end this session. This mode is only intended for testing purpose.
 ```bash
 docker run -p 9000:9000 minio/minio server /export
 ```
 
-Start docker, ephemeral data with consistent name (minio1) and keys (examples shown are from AWS documentation and should be changed):
+## Run Minio Docker Container
+Minio container requires a persistent volume to store configuration and application data. Following command maps local persistent directories from the host OS to virtual config `~/.minio` and export `/export` directories. 
 
 ```bash
 docker run -p 9000:9000 --name minio1 \
-  -e "MINIO_ACCESS_KEY=AKIAIOSFODNN7EXAMPLE" \
-  -e "MINIO_SECRET_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY" \
+  -v /mnt/export/minio1:/export \
+  -v /mnt/config/minio1:/root/.minio \
   minio/minio server /export
 ```
 
-Map export and configuration directories from host for persistence:
-
+## Custom Access and Secret Keys
+To override Minio's auto-generated keys, you may pass secret and access keys explicitly as environment variables. Minio server also allows regular strings as access and secret keys.
 ```bash
 docker run -p 9000:9000 --name minio1 \
+  -e "MINIO_ACCESS_KEY=AKIAIOSFODNN7EXAMPLE" \
+  -e "MINIO_SECRET_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY" \
   -v /mnt/export/minio1:/export \
   -v /mnt/config/minio1:/root/.minio \
   minio/minio server /export