chore: add deepwiki badge at top

Author: nomagick

README.md

@@ -1,6 +1,7 @@
 # Reader
 
 [![codecov](https://codecov.io/gh/jina-ai/reader-saas/branch/main/graph/badge.svg?token=WRECMUUMSz)](https://codecov.io/gh/jina-ai/reader-saas)
+[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/jina-ai/reader)
 
 Your LLMs deserve better input.