Update nativecall.pod6 (#4026)

Closes #4025 

* Update nativecall.pod6

More emphasis how to use Pointer class.

* Update nativecall.pod6

* Update nativecall.pod6

* Update nativecall.pod6

removed trailing space

* Update nativecall.pod6

doc/Language/nativecall.pod6

@@ -187,6 +187,20 @@ When the signature of your native function needs a pointer to some native type
     sub my_version(int32 is rw, int32 is rw) is native('foo') { * }
     my_version(my int32 $major, my int32 $minor); # Pass a pointer to
 
+When you just want to use/pass a pointer using Pointer class you have to
+create the pointers when you declare them. Then you can do this without specifying
+what type it points to. Here is an example:
+
+    use NativeCall;
+    # C prototype is void create_object(void **object)
+    sub create_object(Pointer is rw) is native('foo') { * }
+    my Pointer $p = Pointer.new();
+    create_object($p); # pointer is set by create_object
+
+The C<Pointer> class can be used with types as well e.g. C<Pointer[Str]>.
+Note that Str is a pointer to a string (C<char *> in C/C++). So in that case, you
+can use C<Pointer[Str]> or C<Str>.
+
 Sometimes you need to get a pointer (for example, a library handle) back from a
 C library. You don't care about what it points to - you just need to keep hold
 of it. The C<Pointer> type provides for this.