message: [lite] Update Hexagon guide with new version of hexagon_nn_skel
diff: @@ -79,10 +79,11 @@ dependencies {
  * [v1.14](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.14.run)
  * [v1.17](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.17.0.0.run)
  * [v1.20](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.20.0.0.run)
  + * [v1.21](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.20.0.1.run)
  Note: You will need to accept the license agreement.
  -Note: As of 07/22/2020 you should use v1.20.
  +Note: As of 02/23/2021 you should use v1.21.
  Note: You must use the hexagon_nn libraries with the compatible version of
  interface library. Interface library is part of the AAR and fetched by bazel
  @@ -186,10 +187,11 @@ dependencies {
  * [v1.14](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.14.run)
  * [v1.17](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.17.0.0.run)
  * [v1.20](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.20.0.0.run)
  + * [v1.21](https://storage.cloud.google.com/download.tensorflow.org/tflite/hexagon_nn_skel_v1.20.0.1.run)
  Note: You will need to accept the license agreement.
  -Note: As of 07/22/2020 you should use v1.20.
  +Note: As of 02/23/2021 you should use v1.21.
  Note: You must use the hexagon_nn libraries with the compatible version of
  interface library. Interface library is part of the AAR and fetched by bazel
  