update readme to suggest the latest major version

[staabm]

No description provided.

[staabm]

with my suggested change you run into:

Using version ^2.11 for knplabs/github-api
Using version ^2.0 for php-http/guzzle6-adapter
./composer.json has been created
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - knplabs/github-api 2.11.0 requires php-http/client-implementation ^1.0 -> satisfiable by php-http/guzzle6-adapter[v2.0.0, v2.0.1].
    - php-http/guzzle6-adapter v2.0.0 requires php-http/httplug ^2.0 -> satisfiable by php-http/httplug[v2.0.0].
    - php-http/guzzle6-adapter v2.0.1 requires php-http/httplug ^2.0 -> satisfiable by php-http/httplug[v2.0.0].
    - Can only install one of: php-http/httplug[v2.0.0, v1.1.0].
    - knplabs/github-api 2.11.0 requires php-http/httplug ^1.1 -> satisfiable by php-http/httplug[v1.1.0].
    - Installation request for knplabs/github-api ^2.11 -> satisfiable by knplabs/github-api[2.11.0].


Installation failed, deleting ./composer.json.

.. I guess I am wrong

[acrobat]

@staabm yes indeed, this library is not yet compatible with httplug 2. We are looking into ways to support both versions. See #802

[staabm]

thx for the feedback.

I was mainly confused by the notation, because I read it like
composer require knplabs/github-api php-http/guzzle6-adapter "^1.1" would install the github-api class in version 1.1 but it installs the latest github-api and the ^1.1 only refers to the version of the guzzle adapter.

haven't seen this kind of notation anywhere else before