Removed reference to org-index.el from README

contrib/README

@@ -32,7 +32,6 @@ org-eval.el              --- The <lisp> tag, adapted from Muse
 org-expiry.el            --- Expiry mechanism for Org entries
 org-export-generic.el    --- Export framework for configurable backends
 org-git-link.el          --- Provide org links to specific file version
-org-index.el             --- A personal index for org and beyond
 org-interactive-query.el --- Interactive modification of tags query
 org-invoice.el           --- Help manage client invoices in OrgMode
 org-learn.el             --- SuperMemo's incremental learning algorithm