Improve the formatting a bit

Author: jstasiak

Doc/library/concurrent.futures.rst

@@ -95,9 +95,9 @@ Executor Objects
       returning. The remaining futures are cancelled.
 
       You can avoid having to call this method explicitly if you use the executor
-      as a :term:`context manager` via the  :keyword:`with` statement,
-      which will shutdown the :class:`Executor` (waiting as if
-      :meth:`Executor.shutdown` were called with *wait* set to ``True``)::
+      as a :term:`context manager` via the  :keyword:`with` statement, which
+      will shutdown the :class:`Executor` (waiting as if :meth:`Executor.shutdown`
+      were called with *wait* set to ``True``)::
 
          import shutil
          with ThreadPoolExecutor(max_workers=4) as e: