Minor documentation corrections.

Escape the space after "i.e." (or avoid using it altogether), add missing @ref.

Closes #16235.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76472 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/hashset.h

@@ -204,7 +204,8 @@ public:
     /**
         If an element with the given key is present, the functions returns
         an iterator pointing at that element, otherwise an invalid iterator
-        is returned; i.e.
+        is returned.
+        i.e.
         @code
             hashset.find( non_existent_key ) == hashset.end()
         @endcode