Fix URL fragment target

README.md

@@ -39,7 +39,7 @@ RVM?**](https://github.com/rbenv/rbenv/wiki/Why-rbenv%3F)
   * [Choosing the Ruby Version](#choosing-the-ruby-version)
   * [Locating the Ruby Installation](#locating-the-ruby-installation)
 * [Installation](#installation)
-  * [Homebrew on macOS](#homebrew-on-mac-os)
+  * [Homebrew on macOS](#homebrew-on-macos)
     * [Upgrading with Homebrew](#upgrading-with-homebrew)
   * [Basic GitHub Checkout](#basic-github-checkout)
     * [Upgrading with Git](#upgrading-with-git)