[clang] [clang] document that by default FP turned off for ARM baremetal (PR #122881)

[Ties Stuij via cfe-commits]

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@@ -1076,6 +1076,8 @@ Arm and AArch64 Support
   in leaf functions after enabling ``-fno-omit-frame-pointer``, you can do so by adding
   the ``-momit-leaf-frame-pointer`` option.
 
+- For ARM baremetal targets, the frame pointer (FP) is now turned off by default.
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stuij wrote:

done

https://github.com/llvm/llvm-project/pull/122881