update license file

Author: srinandan

LICENSE renamed to LICENSE.txt

@@ -1,3 +1,4 @@
+
                                  Apache License
                            Version 2.0, January 2004
                         http://www.apache.org/licenses/
@@ -199,5 +200,3 @@
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
-
-[Libraries used by apigeecli including their own licenses - third-party-licenses.md](./third-aprty-licenses.md)