[Docs] Fix Sphinx documentation formatting issues in LanguageExtensions.rst

[codemzs]

Summary

Fix indentation and spacing.

[codemzs]

Fix indentation and spacing.

Hi @pengfei and @rjmccall,

In the previous commit, the Sphinx documentation issues were overlooked due to an unexpected build error and the Sphinx build did not run as part of pre-build check. This was compounded by my unfamiliarity with the documentation generation process.

In this revision, I've addressed the indentation and spacing issues in the .rst files. The fixes have been validated locally using ninja docs-clang-html and ninja docs-llvm-html.

Apologies for the confusion in the previous submission. I look forward to your feedback on this revision.

[pengfei]

LGTM.

clang/docs/LanguageExtensions.rst

 in all language modes, but their support differs between targets.
 A target is said to have "native support" for a type if the target
 processor offers instructions for directly performing basic arithmetic
 on that type.  In the absence of native support, a type can still be
 supported if the compiler can emulate arithmetic on the type by promoting
 to ``float``; see below for more information on this emulation.
 
 * ``__fp16`` is supported on all targets. The special semantics of this
   type mean that no arithmetic is ever performed directly on ``__fp16`` values;
   see below.
 
 * ``_Float16`` is supported on the following targets:
   * 32-bit ARM (natively on some architecture versions)
   * 64-bit ARM (AArch64) (natively on ARMv8.2a and above)
   * AMDGPU (natively)
   * SPIR (natively)
   * X86 (if SSE2 is available; natively if AVX512-FP16 is also available)