Adds pointer to index, closes Raku#4028

Also adds a bit of introduction

doc/Language/nativetypes.pod6

@@ -155,7 +155,7 @@ your programs since it is not part of the Raku specification.
 X<|void type (NativeCall)>
 =head1 The C<void> type
 
-The native C<void> type corresponds to the C C<void> type. Although, being a
+The native C<void> type corresponds to the C namesake type; being a
 valid type, you can use it in expressions:
 
      use NativeCall;
@@ -175,6 +175,12 @@ my Pointer[void] $for-malloc = malloc( 32 );
 say $for-malloc.raku;
 =end code
 
+X<|Pointer>
+As the example shows, it's represented by a parametrized C<Pointer> role,
+using as parameter whatever the original pointer is pointing to (in this
+case, C<void>). This role represents native pointers, and can be used
+wherever they need to be represented in a Raku program.
+
 You can also L<nativecast|/routine/nativecast> L<Blob|/type/Blob>s to this kind
 of pointer in case you need to work with them in native functions that use the
 type