Add fish_update_completions to update if fish binary is found

usr/bin/update

@@ -23,5 +23,15 @@ fi
 echo ""
 
 # Update mlocate index
-pacman -Qq mlocate > /dev/null && echo "Updating mlocate index.." && sudo updatedb
-echo "System updated!"
+if [ -x /usr/bin/fish ]; then 
+    echo "Updating mlocate index.."
+    sudo updatedb
+fi 
+
+# Update fish completions
+if [ -x /usr/bin/fish ]; then 
+    fish -c fish_update_completions
+fi 
+
+echo ""
+echo "System updated! 🐧"