Minor wording change in concurrent.futures. (GH-23194)

Fixes a grammar problem by adding a missing "as", and clarifies the wording of the valid ranges for max_workers.

Author: donkirkby

Doc/library/concurrent.futures.rst

@@ -236,9 +236,9 @@ to a :class:`ProcessPoolExecutor` will result in deadlock.
    An :class:`Executor` subclass that executes calls asynchronously using a pool
    of at most *max_workers* processes.  If *max_workers* is ``None`` or not
    given, it will default to the number of processors on the machine.
-   If *max_workers* is lower or equal to ``0``, then a :exc:`ValueError`
+   If *max_workers* is less than or equal to ``0``, then a :exc:`ValueError`
    will be raised.
-   On Windows, *max_workers* must be equal or lower than ``61``. If it is not
+   On Windows, *max_workers* must be less than or equal to ``61``. If it is not
    then :exc:`ValueError` will be raised. If *max_workers* is ``None``, then
    the default chosen will be at most ``61``, even if more processors are
    available.
@@ -250,7 +250,7 @@ to a :class:`ProcessPoolExecutor` will result in deadlock.
    each worker process; *initargs* is a tuple of arguments passed to the
    initializer.  Should *initializer* raise an exception, all currently
    pending jobs will raise a :exc:`~concurrent.futures.process.BrokenProcessPool`,
-   as well any attempt to submit more jobs to the pool.
+   as well as any attempt to submit more jobs to the pool.
 
    .. versionchanged:: 3.3
       When one of the worker processes terminates abruptly, a