fix: update triton implementation reference (#2002)

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PR #1986 moved the location of the `flash_attn_triton.py` file. This PR
adjusts sources to changes.


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Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>

docs/source/installation_amd.md

@@ -27,7 +27,7 @@ TunableOp is enabled by default, the warmup may take 1-2 minutes. In case you wo
 
 ## Flash attention implementation
 
-Two implementations of Flash Attention are available for ROCm, the first is [ROCm/flash-attention](https://github.com/ROCm/flash-attention) based on a [Composable Kernel](https://github.com/ROCm/composable_kernel) (CK) implementation, and the second is a [Triton implementation](https://github.com/huggingface/text-generation-inference/blob/main/server/text_generation_server/utils/flash_attn_triton.py).
+Two implementations of Flash Attention are available for ROCm, the first is [ROCm/flash-attention](https://github.com/ROCm/flash-attention) based on a [Composable Kernel](https://github.com/ROCm/composable_kernel) (CK) implementation, and the second is a [Triton implementation](https://github.com/huggingface/text-generation-inference/blob/main/server/text_generation_server/layers/attention/flash_attn_triton.py).
 
 By default, the Composable Kernel implementation is used. However, the Triton implementation has slightly lower latency on MI250 and MI300, but requires a warmup which can be prohibitive as it needs to be done again for each new prompt length. If needed, FA Triton impelmentation can be enabled with `--env ROCM_USE_FLASH_ATTN_V2_TRITON="0"` when launching TGI's docker container.