ref-manual: add potential of parallelism to defn of "Task"

(From yocto-docs rev: 2e80de272b987c70374a1758e71c5c1371054d1f)

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Reviewed-by: Quentin Schulz <foss@0leil.ṅet>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/terms.rst

@@ -367,10 +367,16 @@ universal, the list includes them just in case:
      section in the Yocto Project Overview and Concepts Manual.
 
    :term:`Task`
-      A unit of execution for BitBake (e.g.
+      A per-recipe unit of execution for BitBake (e.g.
       :ref:`ref-tasks-compile`,
       :ref:`ref-tasks-fetch`,
       :ref:`ref-tasks-patch`, and so forth).
+      One of the major benefits of the build system is that, since each
+      recipe will typically spawn the execution of numerous tasks,
+      it is entirely possible that many tasks can execute in parallel,
+      either tasks from separate recipes or independent tasks within
+      the same recipe, potentially up to the parallelism of your
+      build system.
 
    :term:`Toaster`
       A web interface to the Yocto Project's :term:`OpenEmbedded Build System`.