Update README

No need to manually initialize the database with a call to `init_db()` as this call is done before `app.run()` in flaskr.py, when you run the file.

examples/flaskr/README

@@ -1,4 +1,3 @@
-
                          / Flaskr /
 
                  a minimal blog application
@@ -14,11 +13,7 @@
          export an FLASKR_SETTINGS environment variable
          pointing to a configuration file.
 
-      2. fire up a python shell and run this:
-
-         >>> from flaskr import init_db; init_db()
-
-      3. now you can run the flaskr.py file with your
+      2. now you can run the flaskr.py file with your
          python interpreter and the application will
          greet you on http://localhost:5000/