Fix code example in README file

Fixes #420
Closes #423

README.md

@@ -30,8 +30,8 @@ Some API methods have optional parameters that can be passed. For example:
 ```go
 client := github.NewClient(nil)
 
-// list recently updated repositories for org "github"
-opt := &github.RepositoryListByOrgOptions{Sort: "updated"}
+// list public repositories for org "github"
+opt := &github.RepositoryListByOrgOptions{Type: "public"}
 repos, _, err := client.Repositories.ListByOrg("github", opt)
 ```
 

github/doc.go

@@ -22,8 +22,8 @@ Some API methods have optional parameters that can be passed. For example:
 
 	client := github.NewClient(nil)
 
-	// list recently updated repositories for org "github"
-	opt := &github.RepositoryListByOrgOptions{Sort: "updated"}
+	// list public repositories for org "github"
+	opt := &github.RepositoryListByOrgOptions{Type: "public"}
 	repos, _, err := client.Repositories.ListByOrg("github", opt)
 
 The services of a client divide the API into logical chunks and correspond to