[doc] Update the document about offline cache (#6313)

Issue: #6263, #4401

Co-authored-by: Yi Xu <[email protected]>

docs/lang/articles/performance_tuning/performance.md

@@ -241,8 +241,6 @@ We address this problem by introducing the *offline* cache feature, which dumps
 To verify the effect, run some examples twice and observe the launch overhead:
 ![](../static/assets/effect_of_offline_cache.png)
 
-For now, the offline cache feature works *only* on the CPU and CUDA backends.
-
 :::note
 If your code behaves abnormally, disable offline cache by setting the environment variable `TI_OFFLINE_CACHE=0` or `offline_cache=False` in the `ti.init()` method call and file an issue with us on [Taichi's GitHub repo](https://github.com/taichi-dev/taichi/issues/new/choose).
 :::