update readme

Signed-off-by: Nico Schottelius <nico@kr.ethz.ch>

README

@@ -108,10 +108,11 @@ how to use cdist.
 There are at least the following branches available:
 
  * master: the development branch
- * 1.6: New types, cleaned up \_\_package* types, internal cleanup
+ * 1.7: Bugfixes, cleanups, new type and explorer rename
 
 Old versions:
 
+ * 1.6: New types, cleaned up \_\_package* types, internal cleanup
  * 1.5: Focus on object orientation instead of global stage orientation
  * 1.4: Support for redefiniton of objects (if equal)
  * 1.3: Support for local and remote code execution (current stable)
@@ -126,7 +127,7 @@ may vanish at any point. To select a specific branch use
     git checkout -b <name> origin/<name>
     
     # Stay on a specific version
-    version=1.6
+    version=1.7
     git checkout -b $version origin/$version
 
 ### Mirrors
@@ -148,6 +149,11 @@ If you stay on a version branche (i.e. 1.0, 1.1., ...), nothing should break.
 The master branch on the other hand is the development branch and may not be
 working, break your setup or eat the tree in your garden.
 
+### Upgrading from 1.6 to 1.7
+
+* If you used the global explorer **hardware_type**, you need to change
+  your code to use **machine** instead.
+
 ### Upgrading from 1.5 to 1.6
 
 * If you used **\_\_package_apt --preseed**, you need to use the new