adding documentation link

README.md

@@ -55,7 +55,8 @@ APEX provides a mechanism for dynamic runtime behavior, either for autotuning or
 Documentation
 =============
 
-Full user documentation is available here: http://uo-oaciss.github.io/apex.
+~~Full user documentation is available here: http://uo-oaciss.github.io/apex.~~ note: outdated!
+In the meantime, please check [the wiki](https://github.com/UO-OACISS/apex/wiki).
 
 The source code is instrumented with Doxygen comments, and the API reference manual can be generated by executing `make doc` in the build directory, after CMake configuration.  [A fairly recent version of the API reference documentation is also available here] (http://www.nic.uoregon.edu/~khuck/apex_docs/doc/html/index.html).