update documentation to specify that TFT master only supports TF 2.x.

PiperOrigin-RevId: 488716253

Author: zoyahav

README.md

@@ -96,7 +96,7 @@ other *untested* combinations may also work.
 
 tensorflow-transform                                                            | apache-beam[gcp] | pyarrow | tensorflow        | tensorflow-metadata | tfx-bsl |
 ------------------------------------------------------------------------------- | -----------------| --------|-------------------|---------------------|---------|
-[GitHub master](https://github.com/tensorflow/transform/blob/master/RELEASE.md) | 2.41.0           | 6.0.0   | nightly (1.x/2.x) | 1.11.0              | 1.11.0  |
+[GitHub master](https://github.com/tensorflow/transform/blob/master/RELEASE.md) | 2.41.0           | 6.0.0   | nightly (2.x)     | 1.11.0              | 1.11.0  |
 [1.11.0](https://github.com/tensorflow/transform/blob/v1.11.0/RELEASE.md)       | 2.41.0           | 6.0.0   | 1.15.5 / 2.10     | 1.11.0              | 1.11.0  |
 [1.10.0](https://github.com/tensorflow/transform/blob/v1.10.0/RELEASE.md)       | 2.40.0           | 6.0.0   | 1.15.5 / 2.9      | 1.10.0              | 1.10.0  |
 [1.9.0](https://github.com/tensorflow/transform/blob/v1.9.0/RELEASE.md)         | 2.38.0           | 5.0.0   | 1.15.5 / 2.9      | 1.9.0               | 1.9.0   |

docs/install.md

@@ -95,7 +95,7 @@ other *untested* combinations may also work.
 
 tensorflow-transform                                                            | apache-beam[gcp] | pyarrow | tensorflow        | tensorflow-metadata | tfx-bsl
 ------------------------------------------------------------------------------- | ---------------- | ------- | ----------------- | ------------------- | -------
-[GitHub master](https://github.com/tensorflow/transform/blob/master/RELEASE.md) | 2.41.0           | 6.0.0   | nightly (1.x/2.x) | 1.11.0              | 1.11.0
+[GitHub master](https://github.com/tensorflow/transform/blob/master/RELEASE.md) | 2.41.0           | 6.0.0   | nightly (2.x)     | 1.11.0              | 1.11.0
 [1.11.0](https://github.com/tensorflow/transform/blob/v1.11.0/RELEASE.md)       | 2.41.0           | 6.0.0   | 1.15.5 / 2.10     | 1.11.0              | 1.11.0
 [1.10.0](https://github.com/tensorflow/transform/blob/v1.10.0/RELEASE.md)       | 2.40.0           | 6.0.0   | 1.15.5 / 2.9      | 1.10.0              | 1.10.0
 [1.9.0](https://github.com/tensorflow/transform/blob/v1.9.0/RELEASE.md)         | 2.38.0           | 5.0.0   | 1.15.5 / 2.9      | 1.9.0               | 1.9.0