Merge branch 'readme-plugins' into 'nightly'

Readme plugins

* Adds several plugin READMEs
  They are pretty basic, but it's a start.

* Changes status.net/wiki URLs to git.gnu.io
  The status.net wiki is dead.

See merge request !103

plugins/OpenID/OpenIDPlugin.php

@@ -597,7 +597,7 @@ class OpenIDPlugin extends Plugin
         $versions[] = array('name' => 'OpenID',
                             'version' => GNUSOCIAL_VERSION,
                             'author' => 'Evan Prodromou, Craig Andrews',
-                            'homepage' => 'http://status.net/wiki/Plugin:OpenID',
+                            'homepage' => 'https://git.gnu.io/gnu/gnu-social/tree/master/plugins/OpenID',
                             'rawdescription' =>
                             // TRANS: Plugin description.
                             _m('Use <a href="http://openid.net/">OpenID</a> to login to the site.'));

plugins/OpenID/README

@@ -0,0 +1,21 @@
+The OpenID plugin allows users to use OpenID to login.
+
+See: http://openid.net/
+
+Installation
+============
+This plugin is enabled by default
+
+Settings
+========
+openidonly: Whether we only allow logins through OpenID.
+trusted_provider: URL to the OpenID provider.
+append_username: Whether to append the username at the end of the OpenID URL
+
+Example
+=======
+$config['site']['openidonly'] = true;
+$config['openid']['trusted_provider'] = "http://example.org";
+$config['openid']['append_username'] = true;
+addPlugin('OpenID');
+