update comment

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/smt/smt_kernel.h

@@ -307,13 +307,13 @@ namespace smt {
 
         /**
            \brief Return a reference to smt::context.
-           This is a temporary hack to support user theories.
-           TODO: remove this hack.
-           We need to revamp user theories too.
+           This breaks abstractions. 
+           
+           It is currently used by the opt-solver
+           to access optimization services from arithmetic solvers
+           and to ensure that the solver has registered PB theory solver.
 
-           This method breaks the abstraction barrier.
-
-           \warning We should not use this method
+           \warning This method should not be used in new code.
         */
         context & get_context();
     };