Update README.md

Remove old announcements (Redesign in progress)

README.md

@@ -14,17 +14,6 @@ can take full advantage of TensorFlow for their research and product development
 
 ## [Announcements](https://github.com/tensorflow/models/wiki/Announcements)
 
-| Date | News |
-|------|------|
-| July 10, 2020 | TensorFlow 2 meets the [Object Detection API](https://github.com/tensorflow/models/tree/master/research/object_detection) ([Blog](https://blog.tensorflow.org/2020/07/tensorflow-2-meets-object-detection-api.html)) |
-| June 30, 2020 | [SpineNet: Learning Scale-Permuted Backbone for Recognition and Localization](https://github.com/tensorflow/models/tree/master/official/vision/detection#train-a-spinenet-49-based-mask-r-cnn) released ([Tweet](https://twitter.com/GoogleAI/status/1278016712978264064)) |
-| June 17, 2020 | [Context R-CNN: Long Term Temporal Context for Per-Camera Object Detection](https://github.com/tensorflow/models/tree/master/research/object_detection#june-17th-2020) released ([Tweet](https://twitter.com/GoogleAI/status/1276571419422253057)) |
-| May 21, 2020 | [Unifying Deep Local and Global Features for Image Search (DELG)](https://github.com/tensorflow/models/tree/master/research/delf#delg) code released |
-| May 19, 2020 | [MobileDets: Searching for Object Detection Architectures for Mobile Accelerators](https://github.com/tensorflow/models/tree/master/research/object_detection#may-19th-2020) released |
-| May 7, 2020 | [MnasFPN with MobileNet-V2 backbone](https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/tf1_detection_zoo.md#mobile-models) released for object detection |
-| May 1, 2020 | [DELF: DEep Local Features](https://github.com/tensorflow/models/tree/master/research/delf) updated to support TensorFlow 2.1 |
-| March 31, 2020 | [Introducing the Model Garden for TensorFlow 2](https://blog.tensorflow.org/2020/03/introducing-model-garden-for-tensorflow-2.html) ([Tweet](https://twitter.com/TensorFlow/status/1245029834633297921)) |
-
 ## Contributions
 
 [![help wanted:paper implementation](https://img.shields.io/github/issues/tensorflow/models/help%20wanted%3Apaper%20implementation)](https://github.com/tensorflow/models/labels/help%20wanted%3Apaper%20implementation)