Fix broken RST links in README and update outdated docs (#794)

Author: veeceey

CHANGES/794.doc

@@ -0,0 +1 @@
+Fixed broken RST hyperlinks in README, added missing ``await`` in docs code example, and updated outdated Python and frozenlist version requirements in documentation to match ``setup.cfg``.

README.rst

@@ -44,9 +44,9 @@ The only available operation is calling the previously registered
 callbacks by using ``await sig.send(data)``.
 
 For concrete usage examples see the `Signals
-<https://docs.aiohttp.org/en/stable/web_advanced.html#aiohttp-web-signals>
+<https://docs.aiohttp.org/en/stable/web_advanced.html#aiohttp-web-signals>`_
 section of the `Web Server Advanced
-<https://docs.aiohttp.org/en/stable/web_advanced.html>` chapter of the `aiohttp
+<https://docs.aiohttp.org/en/stable/web_advanced.html>`_ chapter of the `aiohttp
 documentation`_.
 
 

docs/index.rst

@@ -19,7 +19,7 @@ The callback parameters, which should be passed in the ``.send()`` call, can be
 specified for a type checker::
 
     signal = Signal[int, str](owner)
-    signal.send(42, "foo")
+    await signal.send(42, "foo")
 
 
 For concrete usage examples see the :ref:`aiohttp:aiohttp-web-signals` section of the :doc:`aiohttp:web_advanced` chapter of the :doc:`aiohttp documentation <aiohttp:index>`.