Update README and CHANGELOG

CHANGELOG.md

@@ -7,6 +7,7 @@
 * Move the REST API in the web process and add a ZeroMQ-based API between the web and the master.
 * Move all user management in the web process.
 * Use Postgresql to store the state
+* Rename the zoe-web component in zoe-api to better describe its new role
 
 ## Version 0.9.7
 

README.rst

@@ -17,6 +17,12 @@ Other Zoe resources:
 - Zoe logger: https://github.com/DistributedSystemsGroup/zoe-logger
 
 
+A note on the master branch
+---------------------------
+We are currently redesigning Zoe with a new architecture, so the master branch is unstable and changes very rapidly.
+The latest stable version is maintained under the 0.9.7-stable branch. All the documentation currently refers to this stable version, unless otherwise noted.
+
+
 Repository contents
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