Fix markup

pep-3156.txt

@@ -721,17 +721,17 @@ module is supported on Windows.)
 Signal callbacks
 ''''''''''''''''
 
-- ``add_signal_handler(sig, callback, *args).  Whenever signal ``sig``
+- ``add_signal_handler(sig, callback, *args)``.  Whenever signal
-  is received, arrange for ``callback(*args)`` to be called.
+  ``sig`` is received, arrange for ``callback(*args)`` to be called.
   Specifying another callback for the same signal replaces the
   previous handler (only one handler can be active per signal).  The
   ``sig`` must be a valid sigal number defined in the ``signal``
   module.  If the signal cannot be handled this raises an exception:
-  ``ValueError`` if it is not a valid signal or if it is an uncatchable
+  ``ValueError`` if it is not a valid signal or if it is an
-  signale (e.g. ``SIGKILL``), ``RuntimeError`` if this particular event
+  uncatchable signale (e.g. ``SIGKILL``), ``RuntimeError`` if this
-  loop instance cannot handle signals (since signals are global per
+  particular event loop instance cannot handle signals (since signals
-  process, only an event loop associated with the main thread can
+  are global per process, only an event loop associated with the main
-  handle signals).
+  thread can handle signals).
 
 - ``remove_signal_handler(sig)``.  Removes the handler for signal
   ``sig``, if one is set.  Raises the same exceptions as