Update README.md

Add wiki link and issue queue link to conform it to our README standards

README.md

@@ -5,6 +5,14 @@ This module extends reference fields like the user and node reference fields by
 
 Install this module using the official Backdrop CMS instructions at https://backdropcms.org/guide/modules
 
+## Documentation
+
+Additional documentation is located in [the Wiki](https://github.com/backdrop-contrib/references_dialog/wiki).
+
+## Issues
+
+Bugs and feature requests should be reported in [the Issue Queue](https://github.com/backdrop-contrib/references_dialog/issues).
+
 ## License
 
 This project is GPL v2 software. See the LICENSE.txt file in this directory for complete text.