Mention orphan fragments in doc

docs/cli.rst

@@ -79,7 +79,8 @@ If the fragments directory does not exist, it will be created.
 If the filename exists already, ``towncrier create`` will add (and then increment) a number after the fragment type until it finds a filename that does not exist yet.
 In the above example, it will generate ``123.bugfix.1.rst`` if ``123.bugfix.rst`` already exists.
 
-To create a news fragment not tied to a specific issue, start the fragment name with a ``+``. If that is the entire fragment name, a random hash will be added for you::
+To create a news fragment not tied to a specific issue (which towncrier calls an "orphan fragment"), start the fragment name with a ``+``.
+If that is the entire fragment name, a random hash will be added for you::
 
    $ towncrier create +.feature.rst
    $ ls newsfragments/