docs(docs): add conference slides

Signed-off-by: Nikolas Rimikis <leptopoda@users.noreply.github.com>

docs/README.md

@@ -7,3 +7,8 @@
 ## [Architecture overview](architecture.md)
 
 ## [Login user flow](login.md)
+
+## Nextcloud Conference 2023
+
+We held a lightning talk in the at the Nextcloud conference in 2023 in Berlin.
+You cen check our {slides](nextcloud_conference_talks.pdf) and the recording once available.