update todo and versions of erlang supported

TODO.md

@@ -1,10 +1,18 @@
 # TODO
 
-todo of hackney
-
-- Add Websockets support
-- Add SPDY support
-- Add HTTP pipelines support
-- Add support for custom authentication methods
-- Add support for oauth2 ?
-- Add support for HTTP digest auth
+1.21.0
+------
+
+- Improve pool
+- Improve proxying
+
+2.0.0
+-----
+- Support Websockets 
+- Support HTTP 2
+- Request / Response hooks
+- Dynamic response behaviour.
+
+2.1.0
+-----
+- Support HTTP 3

doc/overview.edoc

@@ -47,15 +47,8 @@
 - Optional socket pool
 - REST syntax: `hackney:Method(URL)' (where a method can be get, post, put, delete, ...)
 
-**Supported versions** of Erlang are R16B03-1, 17.3.4 and above. It is
-reported to work with R14B04 and R15B03-1.
-
-
-**WARNING**: Erlang 17.3 and 17.3.1 have a broken SSL module which
-prevents the usage of SSL connection with some servers. You **must** upgrade
-in that case to Erlang
-[17.3.4](https://github.com/erlang/otp/commit/9417f044ee3c291c2ea343c203aebdcc40597226)
-or superior.
+**Supported versions** of Erlang are 22.3 and above. It is
+reported to work with version from 19.3 to 21.3.
 
 > Note: This is a work in progress, see the
 [TODO](http://github.com/benoitc/hackney/blob/master/TODO.md) for more