mention that we use Debian testing autotools

README

@@ -45,7 +45,8 @@ advantage of their specificities in a portable fashion.
  * if CUDA support is enabled
    * CUDA (version >= 2.2)
    * CUBLAS (version >= 2.2)
- * extra requirements for the svn version
+ * extra requirements for the svn version (we usually use the Debian testing
+   versions)
    * autoconf (version >= 2.60)
    * automake
    * makeinfo