Merge pull request #2918 from hypergig/patch-2

Small docker run example for main README

README.md

@@ -113,6 +113,18 @@ always use separate accounts for play-money and real-money. Unless you manually
 will by default correctly separate the two networks and will not make any accounts available between
 them.*
 
+#### Docker quick start
+
+One of the quickest ways to get Ethereum up and running on your machine is by using Docker:
+
+```
+docker run -d --name ethereum-node -v /Users/alice/ethereum:/root \
+           -p 8545:8545 -p 30303:30303 \
+           ethereum/client-go --fast --cache=512
+```
+
+This will start geth in fast sync mode with a DB memory allowance of 512MB just as the above command does.  It will also create a persistent volume in your home directory for saving your blockchain as well as map the default ports. There is also an `alpine` tag available for a slim version of the image.
+
 ### Programatically interfacing Geth nodes
 
 As a developer, sooner rather than later you'll want to start interacting with Geth and the Ethereum