Periocially check for up to date versions of weave.

README.md

@@ -55,6 +55,12 @@ For installing weave on other platforms, follow the [integration guides](http://
 Weave respects the environment variable `DOCKER_HOST`, so you can run
 it locally to control a weave network on a remote host.
 
+Weave will periodically check with our servers to see if a new version is available. To disable this, run:
+
+```
+CHECKPOINT_DISABLE=true weave launch
+```
+
 ## Quick Start Screencast
 
 <a href="https://youtu.be/kihQCCT1ykE" alt="Click to watch the screencast" target="_blank">