Updated docker docs for location of data path (#1790)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

docs/Configuring-Pantheon/Using-Configuration-File.md

@@ -5,10 +5,6 @@ To specify command line options in a file, use a TOML configuration file.
 The configuration file can be saved and reused across node startups. To specify the configuration file,
 use the [`--config-file`](../Reference/Pantheon-CLI-Syntax.md#config-file) option. 
 
-!!!note
-    The [`--config-file`](../Reference/Pantheon-CLI-Syntax.md#config-file) option is not used when running Pantheon from the [Docker image](../Getting-Started/Run-Docker-Image.md). 
-    Use a bind mount to [specify a configuration file with Docker](../Getting-Started/Run-Docker-Image.md#custom-configuration-file). 
-
 To override an option specified in the configuration file, specify the same option on the command line or as 
 an [environment variable](../Reference/Pantheon-CLI-Syntax.md#pantheon-environment-variables). If an option is specified in multiple places, 
 the order of priority is command line, environment variable, configuration file. 

docs/Deploying-Pantheon/Migration-Docker.md

@@ -36,10 +36,17 @@ was not available and the node key was always read from the data path.
 All file options (for example, [`--config-file`](../Reference/Pantheon-CLI-Syntax.md#config-file)) no longer 
 have a default. Add the relevant command line options to your Pantheon command line and specify the file path. 
 
-The [`--data-path`](../Reference/Pantheon-CLI-Syntax.md#data-path) default is now `/opt/pantheon/database`. 
+The [`--data-path`](../Reference/Pantheon-CLI-Syntax.md#data-path) default is now `/opt/pantheon`. 
 
 The [`--node-private-key-file`](../Reference/Pantheon-CLI-Syntax.md#node-private-key-file) default is 
-now `/opt/pantheon/database/key`. 
+now `/opt/pantheon/key`. 
+
+!!! important 
+    Do not mount a volume at the default data path (`/opt/pantheon`). Mounting a volume at the default 
+    data path path interferes with the operation of Pantheon and prevents Pantheon from safely launching. 
+    
+    To run a node that maintains the node state (key and database), [`--data-path` must be set to a location
+    other than `/opt/pantheon` and a storage volume mounted at that location](../Getting-Started/Run-Docker-Image.md#starting-pantheon). 
 
 The host and port options continue to default to the previously set values. 
 

docs/Getting-Started/Run-Docker-Image.md

@@ -52,25 +52,32 @@ docker run -p <localportJSON-RPC>:8545 -p <localportWS>:8546 -p <localportP2P>:3
      
 ## Starting Pantheon 
 
+!!! important 
+    Do not mount a volume at the default data path (`/opt/pantheon`). Mounting a volume at the default 
+    data path interferes with the operation of Pantheon and prevents Pantheon from safely launching. 
+    
+    To run a node that maintains the node state (key and database), [`--data-path` must be set to a location
+    other than `/opt/pantheon` and a storage volume mounted at that location]. 
+
 ### Run a Node for Testing 
 
 To run a node that mines blocks at a rate suitable for testing purposes with WebSockets enabled: 
 ```bash
-docker run -p 8546:8546 --mount type=bind,source=/<myvolume/pantheon/testnode>,target=/opt/pantheon/database pegasyseng/pantheon:latest --miner-enabled --miner-coinbase fe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-ws-enabled --network=dev
+docker run -p 8546:8546 --mount type=bind,source=/<myvolume/pantheon/testnode>,target=/var/lib/pantheon pegasyseng/pantheon:latest --miner-enabled --miner-coinbase fe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-ws-enabled --network=dev --data-path=/var/lib/pantheon
 ```
 
 ### Run a Node on Rinkeby Testnet 
 
 To run a node on Rinkeby: 
 ```bash
-docker run -p 30303:30303 --mount type=bind,source=/<myvolume/pantheon/rinkeby>,target=/opt/pantheon/database pegasyseng/pantheon:latest --network=rinkeby
+docker run -p 30303:30303 --mount type=bind,source=/<myvolume/pantheon/rinkeby>,target=/var/lib/pantheon pegasyseng/pantheon:latest --network=rinkeby --data-path=/var/lib/pantheon
 ```
 
 ### Run a Node on Ethereum Mainnet 
 
 To run a node on Ethereum mainnet with the HTTP JSON-RPC service enabled: 
 ```bash
-docker run -p 8545:8545 --mount type=bind,source=/<myvolume/pantheon/rinkeby>,target=/opt/pantheon/database  -p 30303:30303 pegasyseng/pantheon:latest --rpc-http-enabled
+docker run -p 8545:8545 --mount type=bind,source=/<myvolume/pantheon/rinkeby>,target=/var/lib/pantheon  -p 30303:30303 pegasyseng/pantheon:latest --rpc-http-enabled --data-path=/var/lib/pantheon
 ```
 
 ## Stopping Pantheon and Cleaning up Resources