Update nightly versions to 2.7 in README (#8490)

README.md

@@ -33,7 +33,7 @@ To install PyTorch/XLA nightly build in a new TPU VM:
 
 ```
 pip3 install --pre torch torchvision --index-url https://download.pytorch.org/whl/nightly/cpu
-pip install 'torch_xla[tpu] @ https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.6.0.dev-cp310-cp310-linux_x86_64.whl' -f https://storage.googleapis.com/libtpu-releases/index.html -f https://storage.googleapis.com/libtpu-wheels/index.html
+pip install 'torch_xla[tpu] @ https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.7.0.dev-cp310-cp310-linux_x86_64.whl' -f https://storage.googleapis.com/libtpu-releases/index.html -f https://storage.googleapis.com/libtpu-wheels/index.html
 ```
 
 ### GPU Plugin
@@ -167,8 +167,9 @@ GPU and nightly builds are available in our public GCS bucket.
 | 2.5 (CUDA 12.4 + Python 3.9) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/cuda/12.4/torch_xla-2.5.0-cp39-cp39-manylinux_2_28_x86_64.whl` |
 | 2.5 (CUDA 12.4 + Python 3.10) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/cuda/12.4/torch_xla-2.5.0-cp310-cp310-manylinux_2_28_x86_64.whl` |
 | 2.5 (CUDA 12.4 + Python 3.11) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/cuda/12.4/torch_xla-2.5.0-cp311-cp311-manylinux_2_28_x86_64.whl` |
-| nightly (Python 3.8) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.6.0.dev-cp38-cp38-linux_x86_64.whl` |
-| nightly (Python 3.10) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.6.0.dev-cp310-cp310-linux_x86_64.whl` |
+| nightly (Python 3.9) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.7.0.dev-cp39-cp39-linux_x86_64.whl` |
+| nightly (Python 3.10) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.7.0.dev-cp310-cp310-linux_x86_64.whl` |
+| nightly (Python 3.11) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/tpuvm/torch_xla-2.7.0.dev-cp311-cp311-linux_x86_64.whl` |
 | nightly (CUDA 12.1 + Python 3.8) | `https://storage.googleapis.com/pytorch-xla-releases/wheels/cuda/12.1/torch_xla-2.6.0.dev-cp38-cp38-linux_x86_64.whl` |
 
 <details>
@@ -186,7 +187,8 @@ The torch wheel version `2.6.0.dev20240925+cpu` can be found at https://download
 
 #### Use nightly build after 08/20/2024
 
-You can also add `yyyymmdd` after `torch_xla-2.6.0.dev` to get the nightly wheel of a specified date. Here is an example:
+You can also add `yyyymmdd` after `torch_xla-2.6.0.dev` (or the latest dev version)
+to get the nightly wheel of a specified date. Here is an example:
 
 ```
 pip3 install torch==2.5.0.dev20240820+cpu --index-url https://download.pytorch.org/whl/nightly/cpu