update docs to reflect that image is now on docker hub

README.md

@@ -15,10 +15,6 @@ Each hosts needs to have the following installed
 
 [pipework]: https://raw.githubusercontent.com/jpetazzo/pipework/master/pipework
 
-(NB. The above assumes that the zettio/weave docker image is
-available. Which it will be once the project is public. Meanwhile,
-you'll have to [build the image yourself](#Building)).
-
 ## Example
 
 Say you have docker running on two hosts, accessible to each other as
@@ -204,6 +200,8 @@ enough.
 
 ## Building
 
+(NB. This is only necessary if you want to work on weave.)
+
 To build weave you need `libpcap-dev` and `docker` installed.
 
 Then simply run