[Doc][Misc] Comprehensive documentation cleanup and grammatical fixes (#8073)

What this PR does / why we need it?
This pull request performs a comprehensive cleanup of the vLLM Ascend
documentation. It fixes numerous typos, grammatical errors, and phrasing
issues across community guidelines, developer documents, hardware
tutorials, and feature guides. Key improvements include correcting
hardware names (e.g., Atlas 300I), fixing broken links, cleaning up code
examples (removing duplicate flags and trailing commas), and improving
the clarity of technical explanations. These changes are necessary to
ensure the documentation is professional, accurate, and easy for users
to follow.

Does this PR introduce any user-facing change?
No, this PR contains documentation-only updates.

How was this patch tested?
The changes were manually reviewed for accuracy and grammatical
correctness. No functional code changes were introduced.

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Signed-off-by: herizhen <1270637059@qq.com>
Signed-off-by: herizhen <59841270+herizhen@users.noreply.github.com>

docs/source/community/versioning_policy.md

@@ -174,4 +174,4 @@ Notes:
 - `torch-npu`: Ascend Extension for PyTorch (torch-npu) releases a stable version to [PyPi](https://pypi.org/project/torch-npu)
   every 3 months, a development version (aka the POC version) every month, and a nightly version every day.
   The PyPi stable version **CAN** be used in vLLM Ascend final version, the monthly dev version **ONLY CAN** be used in
-  vLLM Ascend RC version for rapid iteration, and the nightly version **CANNOT** be used in vLLM Ascend any version and branch.
+  vLLM Ascend RC version for rapid iteration, and the nightly version **CANNOT** be used in vLLM Ascend any version or branch.