docs: remove stale runtime_cache_path compile() setting

[Sujendra-23]

Requested by Sujendra

Description

runtime_cache_path is documented as a compile() / CompilationSettings option, but it is not a field of CompilationSettings any more. The runtime cache moved to RuntimeSettings.runtime_cache (the migration table in docsrc/contributors/runtime_settings.rst already says so). Passing it to compile() goes through CompilationSettings(**compilation_options) and is rejected.

Two docs still describe the old API:

• docsrc/user_guide/compilation/compilation_settings.rst: a runtime_cache_path row in the Engine Caching table. Removed.
• docsrc/tutorials/resource_memory/engine_cache.rst: the "Runtime Cache (TensorRT-RTX)" example passes runtime_cache_path= (and use_python_runtime=True) to dynamo.compile. Replaced with RuntimeSettings(runtime_cache=...) + apply_runtime_settings, and the runtime_cache() context manager, matching docsrc/user_guide/runtime_performance/runtime_settings.rst. The documented default path was also stale (/tmp/torch_tensorrt_engine_cache/...); it now points at RUNTIME_CACHE_PATH in dynamo/_defaults.py.

How I checked: parsed py/torch_tensorrt/dynamo/_settings.py and confirmed CompilationSettings has timing_cache_path but no runtime_cache_path; grepped py/ for runtime_cache_path (no matches); checked that RuntimeSettings, apply_runtime_settings and runtime_cache are exported from torch_tensorrt.runtime. I did not build the Sphinx docs or run the snippet (no GPU / TensorRT-RTX on my machine).

Docs-only change; no code touched.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
• I have added the relevant labels to my PR in so that relevant reviewers are notified

🤖 Generated with Claude Code

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