Add OAuth scope read:org as READ_ORG

This is currently the minimum scope required for getting read access
to the organizations a user is member of. The next broader one would
be "repo" that allows also write access to private repositories which
is much more than required.

Change-Id: Ib18c403a4052fb8385b67f60c5eca062e8646f85

github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java

diff --git a/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java b/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
index 4358c0d..e7a830d 100644
--- a/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
+++ b/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
@@ -50,7 +50,8 @@
     REPO_STATUS("repo_status"),
     DELETE_REPO("delete_repo"),
     NOTIFICATIONS("notifications"),
-    GIST("gist");
+    GIST("gist"),
+    READ_ORG("read:org");
 
     private final String value;