[docs] add an example usage of get_kernel_variants

[sayakpaul]

No description provided.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[sayakpaul]

@danieldk sorry there was a doctest failure which 8fff5a0 should have addressed. Very minor.

[github-actions]

Coverage report — kernels/

Measured on: Python 3.10 / Torch 2.12.0.
Other CI configurations are not included in this number.
Hardware-gated code paths (ROCm/XPU/NPU/Darwin/Windows) are excluded or unreachable on the Linux+CUDA runner.

Total coverage: 84.6% — threshold: 80% — ✅

Per-file breakdown

Name	Stmts	Miss	Cover	Missing
src/kernels/__init__.py	10	0	100%
src/kernels/_system.py	6	1	83%	10
src/kernels/_versions.py	63	7	89%	46, 49, 52-53, 56-57, 100
src/kernels/backends.py	194	55	72%	40, 44, 48-51, 68, 90, 108, 117, 121, 125-127, 148, 170, 181, 188-191, 201, 205-225, 233, 256-276
src/kernels/compat.py	8	1	88%	5
src/kernels/deps.py	54	4	93%	58-59, 95, 98
src/kernels/layer/__init__.py	6	0	100%
src/kernels/layer/_interval_tree.py	103	4	96%	23, 52, 147, 150
src/kernels/layer/device.py	48	14	71%	42, 47-49, 91, 96-98, 101, 149, 152, 155-157
src/kernels/layer/func.py	93	7	92%	72, 100, 154, 257, 263, 272, 290
src/kernels/layer/globals.py	5	0	100%
src/kernels/layer/kernelize.py	73	8	89%	255, 273, 281-282, 288, 292, 308-310
src/kernels/layer/layer.py	174	15	91%	166, 209, 215, 228, 320-321, 333, 342, 350, 361, 390, 394, 407, 460, 490
src/kernels/layer/mode.py	14	0	100%
src/kernels/layer/repos.py	130	34	74%	27, 33, 36-41, 61-62, 68, 71-74, 88, 92, 101-102, 108, 111-114, 121-122, 128, 131-134, 141-142, 148, 151-154, 235
src/kernels/lockfile.py	71	46	35%	37-104, 108-131
src/kernels/status.py	49	2	96%	23, 81
src/kernels/utils.py	322	55	83%	65, 77-81, 87-88, 224, 228, 231, 297, 305, 344-345, 383, 414, 419, 454, 683, 686, 688, 694, 707-708, 732-744, 751-758, 766, 770-780, 784-791, 829, 833, 852, 854
src/kernels/variants.py	262	19	93%	56, 87, 108, 138, 247-248, 289, 291, 371-378, 384-390, 421-427, 439-445, 534-536
src/kernels/verify.py	83	0	100%
TOTAL	1768	272	85%

Updated by the Test kernels workflow on commit d68f8a8d665cccf0849b75c6f8f97909ddc919c2.