README.md: warn about the dev/feature branches

README.md

@@ -57,6 +57,8 @@ Travis status:
 * **[master status](https://travis-ci.org/jreybert/vimagit/branches)**: [![Master build status](https://travis-ci.org/jreybert/vimagit.svg?branch=master)](https://travis-ci.org/jreybert/vimagit/branches)
 * **[next status](https://travis-ci.org/jreybert/vimagit/branches)**: [![next build status](https://travis-ci.org/jreybert/vimagit.svg?branch=next)](https://travis-ci.org/jreybert/vimagit/branches)
 
+A lot a features are developped in dev/feature_name branches. While it may be asked to users to test these branches (during a bug fix for example), one is warned that these branches may be heavily rebased/deleted.
+
 ## TL;DR
 
 This is the minimal required set of command you must know to start playing with vimagit. See [Mapping](#mapping) for a complete description.