added substack logo in readme

.gitignore

@@ -8,6 +8,7 @@
 !*.ipynb
 !*jpeg
 !*svg
+!*.png
 !LICENSE
 !*.gif
 !all_rag_techniques

README.md

@@ -15,7 +15,10 @@ Welcome to one of the most comprehensive and dynamic collections of Retrieval-Au
 
 Don't miss out on cutting-edge developments, new tutorials, and community insights!
 
-**[Subscribe to the RAG Techniques Newsletter of DiamantAI](https://diamantai.substack.com/?r=336pe4&utm_campaign=pub-share-checklist)**
+**[Subscribe to DiamantAI's top 1% AI-focused Newsletter](https://diamantai.substack.com/?r=336pe4&utm_campaign=pub-share-checklist)**
+
+[![DiamantAI's newsletter](images/substack_image.png)](https://diamantai.substack.com/?r=336pe4&utm_campaign=pub-share-checklist)
+
 
 ## Introduction