Update _config.yml

Author: Anasss

_config.yml

@@ -1,9 +1,8 @@
 title: Java 21 OCP Flashcards
 description: A Structured collection of flashcards to help you prepare for the Oracle Certified Professional (OCP) Java 21 exam.
-remote_theme: just-the-docs/just-the-docs
+theme: just-the-docs
 
-plugins:
-  - jekyll-remote-theme
+url: https://just-the-docs.github.io
 
 url: https://anasss.github.io/java21docCards/