PR openxla#15563: [DOC] Document --xla_gpu_require_complete_aot_autotune_results.

Imported from GitHub PR openxla#15563

Copybara import of the project:

--
cddd6fb by Ilia Sergachev <[email protected]>:

[DOC] Document --xla_gpu_require_complete_aot_autotune_results.

Merging this change closes openxla#15563

COPYBARA_INTEGRATE_REVIEW=openxla#15563 from openxla:doc_determinism_flag cddd6fb
PiperOrigin-RevId: 658750072

Author: sergachev

docs/determinism.md

@@ -8,6 +8,10 @@ once and avoid it in subsequent compilations. Otherwise due to fluctuations in
 measurements different kernels can be picked as the fastest ones in different
 compilation runs.
 
+`--xla_gpu_require_complete_aot_autotune_results` can be used to ensure that no
+autotuning happens on repeated compilations - they either reuse compatible
+results of previous runs or fail.
+
 ## Execution
 
 Programs compiled by XLA can be non-deterministic on operations like scatter,