doc fixes

Author: jll63

doc/headers_namespaces.adoc

@@ -51,7 +51,7 @@ in scope, or with qualified names.
 as the overrider itself. It "calls" the guide function in a non-evaluated
 context, passing it a `std::ostream&` and a `virtual_ptr<Cat>`. The return type
 of the guide function is the method to add the overrider to. Exactly one guide
-function must match. The normal rules of overload resolution apply. In this
+function must match. The normal rules of overload resolution apply. In that
 case, the guide function is found via argument dependant lookup (ADL).
 
 The macro adds several constructs to the current namespace:

doc/with_vptr.adoc

@@ -3,7 +3,7 @@
 
 ### Synopsis
 
-Defined in <boost/openmethod/core.hpp>.
+Defined in <boost/openmethod/with_vptr.hpp>.
 
 ```c++
 namespace boost::openmethod {