bpo-35716: Update time.CLOCK_MONOTONIC_RAW doc (GH-11517)

Document that the time.CLOCK_MONOTONIC_RAW constant
is now also available on macOS 10.12.

Co-authored-by: Ricardo Fraile <rfraile@rfraile.eu>

Doc/library/time.rst

@@ -772,7 +772,7 @@ These constants are used as parameters for :func:`clock_getres` and
    Similar to :data:`CLOCK_MONOTONIC`, but provides access to a raw
    hardware-based time that is not subject to NTP adjustments.
 
-   Availability: Linux 2.6.28 or later.
+   .. availability:: Linux 2.6.28 and newer, macOS 10.12 and newer.
 
    .. versionadded:: 3.3
 
@@ -799,7 +799,7 @@ These constants are used as parameters for :func:`clock_getres` and
 
    Thread-specific CPU-time clock.
 
-   Availability: Unix.
+   .. availability::  Unix.
 
    .. versionadded:: 3.3