about: update the slide deck

Author: stanislaw

README.md

@@ -4,5 +4,5 @@ The documentation is hosted on Read the Docs:
 [StrictDoc documentation](https://strictdoc.readthedocs.io/en/stable/).
 
 For a quick overview of the project, check out the
-[StrictDoc project](https://github.com/strictdoc-project/strictdoc/blob/main/about/StrictDoc_SlideDeck.pdf)
+[StrictDoc project](https://github.com/strictdoc-project/strictdoc/blob/main/about/StrictDoc.pdf)
 slide deck.