Update index.md

Just adjusted a space, now it's more readable

src/data/roadmaps/cpp/content/105-pointers-and-references/index.md

@@ -28,7 +28,8 @@ int add(int a, int b)
 }
 
 int main()
-{   int (*funcptr) (int, int) = add; // Pointer 'funcptr' now points to the functions 'add'
+{
+  int (*funcptr) (int, int) = add; // Pointer 'funcptr' now points to the functions 'add'
   funcptr(4, 5); // Return 9
 }
 ```