Simplified index.md (#29285)

Simplified the logic of nested loops of pattern printing.

guide/english/c/arrays/index.md

@@ -130,7 +130,7 @@ int main() {
         for (int col = 0; col < cols; col++) {
             printf("%5d", arr[row][col]);
         }
-        puts("");
+        printf("\n");
     }
 
     return 0;