Fix the Clang sphinx build

This addresses issues found by:
https://lab.llvm.org/buildbot/#/builders/92/builds/50402

clang/docs/UsersManual.rst

@@ -1725,17 +1725,17 @@ floating point semantic models: precise (the default), strict, and fast.
    Details:
 
    * ``precise`` Disables optimizations that are not value-safe on
-    floating-point data, although FP contraction (FMA) is enabled
-    (``-ffp-contract=on``). This is the default behavior. This value resets
-    ``-fmath-errno`` to its target-dependent default.
+     floating-point data, although FP contraction (FMA) is enabled
+     (``-ffp-contract=on``). This is the default behavior. This value resets
+     ``-fmath-errno`` to its target-dependent default.
    * ``strict`` Enables ``-frounding-math`` and
-    ``-ffp-exception-behavior=strict``, and disables contractions (FMA).  All
-    of the ``-ffast-math`` enablements are disabled. Enables
-    ``STDC FENV_ACCESS``: by default ``FENV_ACCESS`` is disabled. This option
-    setting behaves as though ``#pragma STDC FENV_ACCESS ON`` appeared at the
-    top of the source file.
+     ``-ffp-exception-behavior=strict``, and disables contractions (FMA).  All
+     of the ``-ffast-math`` enablements are disabled. Enables
+     ``STDC FENV_ACCESS``: by default ``FENV_ACCESS`` is disabled. This option
+     setting behaves as though ``#pragma STDC FENV_ACCESS ON`` appeared at the
+     top of the source file.
    * ``fast`` Behaves identically to specifying both ``-ffast-math`` and
-    ``ffp-contract=fast``
+     ``ffp-contract=fast``
 
    Note: If your command line specifies multiple instances
    of the ``-ffp-model`` option, or if your command line option specifies