Update README.md

Added a section to track major changes.

README.md

@@ -67,3 +67,10 @@ modification, are permitted provided that the following conditions are met:
  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
  WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE.
+
+## Major Changes
+
+#### Ver. 0.3
+
+1. Removes ``quantecon/models`` subpackage and the collection of code examples. Code has been migrated to the [QuantEcon.applications](https://github.com/QuantEcon/QuantEcon.applications) repository.
+2. Adds a utility for fetching notebook dependencies from [QuantEcon.applications](https://github.com/QuantEcon/QuantEcon.applications) to support community contributed notebooks.