docs: add hoverxref & codeautolink support. Various fixes

docs/source/contributing.rst

@@ -203,6 +203,8 @@ it being merely hard to fix). For example:
 
 .. code:: python
 
+    if ...:
+        ...
     else:  # pragma: no cover
         raise AssertionError("this can't happen!")
 

docs/source/design.rst

@@ -382,11 +382,11 @@ Specific style guidelines
 
   .. code:: python
 
-     def call_the_thing(fn, *args, kwonly1, kwonly2, ...):
+     def call_the_thing(fn, *args, kwonly1, kwonly2):
          ...
 
   where ``fn(*args)`` is the thing to be called, and ``kwonly1``,
-  ``kwonly2``, ... are keyword-only arguments that belong to
+  ``kwonly2``, are keyword-only arguments that belong to
   ``call_the_thing``. This applies even if ``call_the_thing`` doesn't
   take any arguments of its own, i.e. in this case its signature looks
   like:
@@ -420,10 +420,10 @@ Specific style guidelines
 
   .. code:: python
 
-     async def OPERATION(...):
+     async def OPERATION(arg1, arg2):
          ...
 
-     def OPERATION_nowait(...):
+     def OPERATION_nowait(arg1, arg2):
          ...
 
   and the ``nowait`` version raises :exc:`trio.WouldBlock` if it would block.

docs/source/reference-io.rst

@@ -378,7 +378,7 @@ broken features:
 
   .. code:: python
 
-     _, service_name = await getnameinfo((127.0.0.1, port), NI_NUMERICHOST))
+     _, service_name = await getnameinfo(('127.0.0.1', port), NI_NUMERICHOST)
 
 * :func:`~socket.getservbyname`: obsolete and `buggy
   <https://bugs.python.org/issue30482>`__; instead, do:

docs/source/reference-lowlevel.rst

@@ -711,7 +711,8 @@ can use as a model:
 
 .. code:: python
 
-    import asyncio, trio
+    import asyncio
+    import trio
 
     # A tiny Trio program
     async def trio_main():