chore(deps): add bundler ecosystem to dependabot

Adds bundler package ecosystem to Dependabot configuration to monitor
Jekyll gems in docs/ directory for security updates and dependency bumps.

Signed-off-by: sonupreetam <[email protected]>

Author: sonupreetam

.github/dependabot.yaml

@@ -27,3 +27,16 @@ updates:
         update-types:
           - "minor"
           - "patch"
+  - package-ecosystem: "bundler"
+    directory: "/docs"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "chore(deps)"
+    labels: ["ruby", "dependencies"]
+    groups:
+      dependencies:
+        applies-to: version-updates
+        update-types:
+          - "minor"
+          - "patch"