http2: minor update of the README

lib/README.http2

 
 HTTP2 with libcurl
 
- Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2-06
+ Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2
 
  nghttp2 (https://github.com/tatsuhiro-t/nghttp2)
 
-  We're depending on this 3rd party library for the actual low level protocol
-  handling parts. The reason for this is that HTTP2 is much more complex at
-  that layer than HTTP1.1 (which we implement on our own) and that nghttp2 is
-  an already existing and well functional library.
+  libcurl uses this 3rd party library for the low level protocol handling
+  parts. The reason for this is that HTTP2 is much more complex at that layer
+  than HTTP1.1 (which we implement on our own) and that nghttp2 is an already
+  existing and well functional library.
+
+  Right now, nghttp2 implements http2 draft-09
 
  Over an http:// URL
 
   If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will include
   an upgrade header in the initial request to the host to allow upgrading to
-  http2. Possibly introduce an option that will cause libcurl to fail if not
-  possible to upgrade. Possibly introduce an option that makes libcurl use
-  http2 at once over http://
+  http2.
+
+  Possibly we can later introduce an option that will cause libcurl to fail if
+  not possible to upgrade. Possibly we introduce an option that makes libcurl
+  use http2 at once over http://
 
  Over an https:// URL
 
   If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will use ALPN
   (or NPN) to negotiate which protocol to continue with. Possibly introduce an
   option that will cause libcurl to fail if not possible to use http2.
+  Consider options to explicitly disable ALPN and/or NPN.
+
+SSL libs
+
+  The challange is the ALPN and NPN support and all our different SSL
+  backends.  Right now we support ALPN and VPN with OpenSSL and ALPN with
+  GnuTLS.
+
+Applications
+
+  We hide http2's binary nature and convert received http2 traffic to headers
+  in HTTP 1.1 style. This allows applications to work unmodified.
+
+curl tool
+
+  curl offers the --http2 command line option to enable use of http2
 
 To consider: