Fix spelling in WIT readme (#2275)

Author: jameswex

tensorboard/plugins/interactive_inference/README.md

@@ -298,7 +298,7 @@ jupyter nbextension enable --py --sys-prefix witwidget
 Note that if you use TensorFlow with GPU support (tensorflow-gpu), then you
 should instead install the GPU-compatible version of witwidget:
 ```sh
-pip install widwidget-gpu
+pip install witwidget-gpu
 jupyter nbextension install --py --symlink --sys-prefix witwidget
 jupyter nbextension enable --py --sys-prefix witwidget
 ```
@@ -312,7 +312,7 @@ containing:
 ```
 !pip install witwidget
 ```
-For TensorFlow GPU support, use the widwidget-gpu package instead of witwidget.
+For TensorFlow GPU support, use the witwidget-gpu package instead of witwidget.
 
 Then, use it as seen at the bottom of the
 [What_If_Tool_Notebook_Usage.ipynb notebook](https://colab.research.google.com/github/tensorflow/tensorboard/blob/master/tensorboard/plugins/interactive_inference/What_If_Tool_Notebook_Usage.ipynb).