Update readme (#578)

* update README

* update issue link in readme

Author: xiantang

README.md

@@ -259,7 +259,8 @@ Should use `\` to escape the `' in the bin. related issue: [#305](https://github
 
 ### How to Reload the Browser Automatically on Static File Changes
 
-Refer to issue #512 for additional details.
+
+Refer to issue [#512](https://github.com/cosmtrek/air/issues/512) for additional details.
 
 * Ensure your static files in `include_dir`, `include_ext`, or `include_file`.
 * Activate the proxy by configuring the following config: