Added Docker image migration content (#1692)

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

CHANGELOG.md

@@ -2,7 +2,12 @@
 
 ### Java 11 Required from v1.2
 
-From v1.2, Pantheon will require Java 11.  That is, Pantheon on Java 8 will no longer be supported.
+From v1.2, Pantheon requires Java 11.  Pantheon on Java 8 is no longer supported.
+
+### Docker Image Migration 
+
+In v1.2, we removed the entry-point script from our Docker image. Refer to the [migration guide](https://docs.pantheon.pegasys.tech/en/latest/Deploying-Pantheon/High-Availability/)
+for information on options that were previously automatically added to the Pantheon command line. 
 
 ## 1.1.4 
 

docs/Deploying-Pantheon/Migration-Docker.md

@@ -0,0 +1,49 @@
+description: Migrating from pre v1.2 Docker image to v1.2 Docker image  
+<!--- END of page meta data -->
+
+# Migrating from pre-1.2 Docker Image to 1.2+
+
+## Before v1.2
+
+The Pantheon Docker image had an entry-script that automatically added a number of options 
+to the Pantheon command line. The options could not be set using command line arguments.  
+
+The options automatically added to the Pantheon command line for the Pantheon Docker image before v1.2 were: 
+
+* If the file existed: 
+    
+    - [`--config-file /etc/pantheon/pantheon.conf`](../Reference/Pantheon-CLI-Syntax.md#config-file)
+    - [`--genesis-file /etc/pantheon/genesis.json`](../Reference/Pantheon-CLI-Syntax.md#genesis-file)
+    - [`--rpc-http-authentication-credentials-file /etc/pantheon/rpc_http_auth_config.toml`](../Reference/Pantheon-CLI-Syntax.md#rpc-http-authentication-credentials-file) 
+    - [`--rpc-ws-authentication-credentials-file /etc/pantheon/rpc_ws_auth_config.toml`](../Reference/Pantheon-CLI-Syntax.md#rpc-ws-authentication-credentials-file)
+    - [`--privacy-public-key-file /etc/pantheon/privacy_public_key`](../Reference/Pantheon-CLI-Syntax.md#privacy-public-key-file)
+    - [`--permissions-nodes-config-file /etc/pantheon/permissions_config.toml`](../Reference/Pantheon-CLI-Syntax.md#permissions-nodes-config-file)
+    - [`--permissions-accounts-config-file /etc/pantheon/permissions_config.toml`](../Reference/Pantheon-CLI-Syntax.md#permissions-accounts-config-file)
+
+* [`--data-path /var/lib/pantheon`](../Reference/Pantheon-CLI-Syntax.md#data-path) 
+* [`--rpc-http-host=0.0.0.0`](../Reference/Pantheon-CLI-Syntax.md#rpc-http-host)
+* [`--rpc-http-port=8545`](../Reference/Pantheon-CLI-Syntax.md#rpc-http-port)
+* [`--rpc-ws-host=0.0.0.0`](../Reference/Pantheon-CLI-Syntax.md#rpc-ws-host)
+* [`--rpc-ws-port=8546`](../Reference/Pantheon-CLI-Syntax.md#rpc-ws-port)
+* [`--p2p-host=0.0.0.0`](../Reference/Pantheon-CLI-Syntax.md#p2p-host)
+* [`--p2p-port=30303`](../Reference/Pantheon-CLI-Syntax.md#p2p-port)
+
+The [`--node-private-key-file`](../Reference/Pantheon-CLI-Syntax.md#node-private-key-file) command line option
+was not available and the node key was always read from the data path. 
+
+## From v1.2 
+
+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 [`--node-private-key-file`](../Reference/Pantheon-CLI-Syntax.md#node-private-key-file) default is 
+now `/opt/pantheon/database/key`. 
+
+The host and port options continue to default to the previously set values. 
+
+!!! tip
+    All command line options can be set using [environment variables](../Reference/Pantheon-CLI-Syntax.md#pantheon-environment-variables). 
+
+

mkdocs.yml

@@ -128,6 +128,7 @@ nav:
           - Alethio EthStats Lite Network Monitor: Monitoring/Alethio/Lite-Network-Monitor.md
     - Deploying Pantheon:
         - High Availability: Deploying-Pantheon/High-Availability.md
+        - Migrating Docker Image: Deploying-Pantheon/Migration-Docker.md
     - Troubleshooting:
         - Troubleshooting: Troubleshooting/Troubleshooting.md
     - Reference: