add note about nvm in readme

readme.md

@@ -17,8 +17,15 @@ engine. The secret key is stored in the URL [fragment identifier] which is never
 the server but is available to javascript so by sharing the URL, you give authorization
 to others who want to participate.
 
-To install:
 
+# Installation
+
+Cryptpad depends on the Nodejs runtime.
+We recommend installing it via [NVM](https://github.com/creationix/nvm "Node Version Manager") to ensure that you are running an up to date version.
+
+Once you have a recent runtime:
+
+```
 git clone <this repo>
 cd cryptpad
 npm install
@@ -33,6 +40,7 @@ To install:
 $EDITOR config.js
 
 node ./server.js
+```
 
 ## Maintenance