update Slack/ remove help wanted

Author: zsdonghao

README.md

@@ -22,8 +22,7 @@ TensorLayer is a deep learning and reinforcement learning library based on [Goog
 * Release [Flickr dataset loader](http://press.liacs.nl/mirflickr/mirdownload.html), see [load_flickr25k](http://tensorlayer.readthedocs.io/en/latest/modules/files.html#flickr25k) and [load_flickr1M](http://tensorlayer.readthedocs.io/en/latest/modules/files.html#flickr1m).
 * Release [SpatialTransformer2dAffineLayer](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#spatial-transformer) for [Spatial Transformer Networks](https://github.com/zsdonghao/Spatial-Transformer-Nets) see [example code](https://github.com/zsdonghao/Spatial-Transformer-Nets).
 * Release [Sub-pixel Convolution 2D](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#super-resolution-layer) for Super-resolution see [SRGAN code](https://github.com/zsdonghao/SRGAN).
-* Join [Slack](https://join.slack.com/t/tensorlayer/shared_invite/MjExMjMzODAwNjI0LTE0OTk4ODEzMjUtNmVjNjQ4ZjMzMw) Now.
-* [Attention Seq2seq](https://github.com/zsdonghao/tensorlayer/issues/164) help wanted.
+* Join [Slack](https://join.slack.com/t/tensorlayer/shared_invite/MjI1NjQ5NTUxOTY5LTE1MDI3MDYwNTItYzYwNmFiZmZkOA) Now.
 * You can now use TensorLayer with [TF-Slim](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#connect-tf-slim) and [Keras](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#connect-keras) together!
 
 # Design Philosophy