add version compatibility table

Author: fbourigault

README.md

@@ -21,12 +21,13 @@ You can visit [HTTPlug for library users](http://docs.php-http.org/en/latest/htt
 Versioning
 ----------
 
-From the 6.0 stable release of Gitlab, I shall now be matching the client version with the Gitlab version. For example
-when Gitlab 6.1 is released I will release version 6.1.0 of the API client. If I need to make future updates to the client
-before the next API version is released, I'll simply use a 3rd build version - `6.1.1`, `6.1.2` etc for example.
+Depending on your Gitlab server version, you must choose the right version of this library.
+Please refer to the following table to pick the right one.
 
-It is recommended that you keep your composer file in sync with whatever version of Gitlab you are currently running:
-if you are using 6.0, you should require `6.0.*`; 6.1 should be `6.1.*`...
+|Version|Gitlab API Version|Gitlab Version|
+|-------|------------------|--------------|
+|9.x    | V4               | >= 9.0       |
+|8.x    | V3               | < 9.5        |
 
 General API Usage
 -----------------