docs(readme): update torch urls

README.md

@@ -115,15 +115,15 @@ Install this via pip (or your favourite package manager that uses pip):
 
 ```shell
 python -m pip install -U pip setuptools wheel
-pip install -U torch torchaudio --index-url https://download.pytorch.org/whl/cu118
+pip install -U torch torchaudio --index-url https://download.pytorch.org/whl/cu118 # https://download.pytorch.org/whl/nightly/cu121
 pip install -U so-vits-svc-fork
 ```
 
 <details>
   <summary>Notes</summary>
 
 - If no GPU is available or using MacOS, simply remove `pip install -U torch torchaudio --index-url https://download.pytorch.org/whl/cu118`. MPS is probably supported.
-- If you are using an AMD GPU on Linux, replace `--index-url https://download.pytorch.org/whl/cu118` with `--index-url https://download.pytorch.org/whl/rocm5.4.2`. AMD GPUs are not supported on Windows ([#120](https://github.com/34j/so-vits-svc-fork/issues/120)).
+- If you are using an AMD GPU on Linux, replace `--index-url https://download.pytorch.org/whl/cu118` with `--index-url https://download.pytorch.org/whl/nightly/rocm5.6`. AMD GPUs are not supported on Windows ([#120](https://github.com/34j/so-vits-svc-fork/issues/120)).
   </details>
 
 ### Update