add link to "Org-Dex.el"

see https://github.com/nitincodery/org-dex.el

README.MD

@@ -154,6 +154,8 @@ Footnotes:
   https://github.com/sissbruecker/linkding
 - obsidian-html-plugin - Plugin for reading HTML pages in Obsidian:
   https://github.com/nuthrash/obsidian-html-plugin
+- Org-Dex.el - Emacs package designed to enhance Org-mode by integrating the 
+  SingleFile CLI: https://github.com/nitincodery/org-dex.el
 - Petal Cite Web Importer - Browser extension to save PDFs and capture web pages
   in Petal Cite: https://github.com/ks-collab/cite-extension
 - Pocket Search Engine - Semantic search app for Android that works entirely