Update README.md

README.md

@@ -146,6 +146,7 @@ The README with the procedures and tips the team used during this porting effort
     * **hip_runtime_api.h** : Defines HIP runtime APIs and can be compiled with many standard Linux compilers (hcc, GCC, ICC, CLANG, etc), in either C or C++ mode.
     * **hip_runtime.h** : Includes everything in hip_runtime_api.h PLUS hipLaunchKernel and syntax for writing device kernels and device functions.  hip_runtime.h can only be compiled with hcc.
     * **hcc_detail/**** , **nvcc_detail/**** : Implementation details for specific platforms.  HIP applications should not include these files directly.
+    * **hcc.h** : Includes interop APIs for HIP and HCC
     
 * **bin**: Tools and scripts to help with hip porting
     * **hipify** : Tool to convert CUDA code to portable CPP.  Converts CUDA APIs and kernel builtins.