CPP13 — Read-only parameter remnants

in the resolution to issue 863, we decided to get rid of the read-only
restriction for parameters. However, we forgot to remove a few snippets.

Page 1-110, table, case 3:

Remove the following text:

Following the completion of a request, the caller is not allowed
to modify any values in the returned storage--to do so, the
caller must first copy the returned instance into a new instance,
then modify the new instance.

Page 1-110, table, case 6:

Remove the following text:

Following completion of a request, the caller is not allowed
to modify any values in the returned storage--to do so, the
caller must first copy the returned array instance into a new
array instance, then modify the new instance.