Adds a short description to the main landing page of our GitHub repo …

…to point users to the tf.org subsite.

PiperOrigin-RevId: 381912238

README.md

@@ -30,6 +30,7 @@ version of TF Text (eg. for tensorflow==2.3.x use tensorflow_text==2.3.x).
 
 ## INDEX
 * [Introduction](#introduction)
+* [Documentation](#documentation)
 * [Unicode](#unicode)
 * [Normalization](#normalization)
 * [Tokenization](#tokenization)
@@ -58,6 +59,12 @@ in the TensorFlow graph. You do not need to worry about tokenization in
 training being different than the tokenization at inference, or managing
 preprocessing scripts.
 
+## Documentation
+
+Please visit [http://tensorflow.org/text](http://tensorflow.org/text) for all
+documentation. This site includes API docs, guides for working with TensorFlow
+Text, as well as tutorials for building specific models.
+
 ## Unicode
 
 Most ops expect that the strings are in UTF-8. If you're using a different