[clang] [docs] Pass -c when generating a PCH file (PR #226850)

[Fangrui Song via cfe-commits]

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@@ -1527,13 +1527,13 @@ compilation on systems with very large system headers (e.g., macOS).
 
 #### Generating a PCH File
 
-To generate a PCH file using Clang, one invokes Clang with the
-`-x <language>-header` option. This mirrors the interface in GCC
-for generating PCH files:
+To generate a PCH file, compile the header with `-c`, using
+`-x <language>-header` if the file extension does not identify it as a
+header. This mirrors the interface in GCC for generating PCH files:
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MaskRay wrote:

Thanks for the link! I'm glad that One sentence per line is now the rule. Updated my CLAUDE.md

https://github.com/llvm/llvm-project/pull/226850