Remove hooks from the user guide

They're gone!

doc/src/guide/book.asciidoc

@@ -96,6 +96,4 @@ include::architecture.asciidoc[Architecture]
 
 include::broken_clients.asciidoc[Dealing with broken clients]
 
-include::hooks.asciidoc[Hooks]
-
 include::overview.asciidoc[Overview]

doc/src/guide/hooks.asciidoc

@@ -1,46 +0,0 @@
-[[hooks]]
-== Hooks
-
-Hooks allow the user to customize Cowboy's behavior during specific
-operations.
-
-=== Onresponse
-
-The `onresponse` hook is called right before sending the response
-to the socket. It can be used for the purposes of logging responses,
-or for modifying the response headers or body. The best example is
-providing custom error pages.
-
-Note that this function MUST NOT crash. Cowboy may or may not send a
-reply if this function crashes. If a reply is sent, the hook MUST
-explicitly provide all headers that are needed.
-
-You can specify the `onresponse` hook when creating the listener.
-
-[source,erlang]
-----
-cowboy:start_http(my_http_listener, 100,
-    [{port, 8080}],
-    [
-        {env, [{dispatch, Dispatch}]},
-        {onresponse, fun ?MODULE:custom_404_hook/4}
-    ]
-).
-----
-
-The following hook function will provide a custom body for 404 errors
-when it has not been provided before, and will let Cowboy proceed with
-the default response otherwise.
-
-[source,erlang]
-----
-custom_404_hook(404, Headers, <<>>, Req) ->
-    Body = <<"404 Not Found.">>,
-    Headers2 = lists:keyreplace(<<"content-length">>, 1, Headers,
-        {<<"content-length">>, integer_to_list(byte_size(Body))}),
-    cowboy_req:reply(404, Headers2, Body, Req);
-custom_404_hook(_, _, _, Req) ->
-    Req.
-----
-
-Again, make sure to always return the last request object obtained.

doc/src/guide/streams.asciidoc

@@ -11,5 +11,4 @@ pre-release.
 Streams are meant to replace hooks. The relevant chapters
 for Cowboy 1.0 were:
 
-* xref:hooks[Hooks]
 * xref:broken_clients[Dealing with broken clients]