qapi: modify docstrings to be sphinx-compatible

A precise style guide and a package-wide overhaul is forthcoming pending
further discussion and consensus. For now, merely avoid obvious errors
that cause Sphinx documentation build problems, using a style loosely
based on PEP 257 and Sphinx Autodoc. It is chosen for interoperability
with our existing Sphinx framework, and because it has loose recognition
in the Pycharm IDE.

See also:

https://www.python.org/dev/peps/pep-0257/
https://www.sphinx-doc.org/en/master/usage/restructuredtext/domains.html#info-field-lists
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20201009161558.107041-3-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

scripts/qapi/gen.py

@@ -154,9 +154,11 @@ def _bottom(self):
 
 @contextmanager
 def ifcontext(ifcond, *args):
-    """A 'with' statement context manager to wrap with start_if()/end_if()
+    """
+    A with-statement context manager that wraps with `start_if()` / `end_if()`.
 
-    *args: any number of QAPIGenCCode
+    :param ifcond: A list of conditionals, passed to `start_if()`.
+    :param args: any number of `QAPIGenCCode`.
 
     Example::