Update NEWS.md

Author: fverdugo

NEWS.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.7.0] - 2020-02-13
+
+This version is a major refactoring of the project which is not summarized here for the sake of brevity. Most of the functionality of v0.6.0 is available in v0.7.0, but with a possibly slightly different API. See the changes in the sources of the Gridap Tutorials between versions 0.6.0 and 0.7.0 to effectively see the major changes in the API. 
+
 ## [0.6.0] - 2020-01-24
 ### Added
 - New `GenericRefFE`. Since commit [876ef1e](https://github.com/gridap/Gridap.jl/commit/c3c9010177432b8f07aaecf4a0baa4b93876ef1e)