Document how to access private repos

[Nyholm]

Question in #471 and the solution is in #440.

This should be somewhere in the readme.

[josephmancuso]

yeah why isn't this in the docs? took me a long time to figure out that the code is:

$client = new \Github\Client(); 
$client->authenticate("oauth_api_token_here", null, \Github\Client::AUTH_HTTP_TOKEN);
$publicAndPrivateRepos= $client->currentUser()->repositories();

this took me a long time to figure out while looking through the docs. I think it should be in the doc/repos.md somewhere as that's the logical place to look for public and private repos retrieval. I believe the docs are broken up by api type so even just a note in those docs to look at the currentUser docs would be fine. Also the currentuser docs seem really incomplete.

i'll be able to put together a PR if needed

[acrobat]

Please open a PR with any improvements you've found necessary, this is the only way this project can improve! Thank!

[josephmancuso]

ok will do. thanks

[acrobat]

Fixed in #671