Repair sphinx doc generation

[bob80905]

Summary

mistake in the log commit neglected to place a space after the `` literal,
which messed up the build by incapacitating the sphinx generator.

[beanz]

LGTM

clang/docs/ReleaseNotes.rst

* The hard-float ABI is now available in Armv8.1-M configurations that
   have integer MVE instructions (and therefore have FP registers) but
   no scalar or vector floating point computation. Previously, trying
   to select the hard-float ABI on such a target (via
   ``-mfloat-abi=hard`` or a triple ending in ``hf``) would silently
   use the soft-float ABI instead.
 
 Floating Point Support in Clang
 -------------------------------
-- Add ``__builtin_elementwise_log``builtin for floating point types only.
+- Add ``__builtin_elementwise_log`` builtin for floating point types only.
 
 Internal API Changes
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 Build System Changes
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 AST Matchers