feat: update README to include openacc

README.md

@@ -50,6 +50,9 @@ This version of XSBench is written in SYCL, and can be used for CPU, GPU, FPGA,
 5. **XSBench/hip**
 This version of XSBench is written in HIP for use with GPU architectures. This version is derived from CUDA using an automatic conversion tool with only a few small manual changes.
 
+6. XSBench/openacc
+This verison of XSBench is written in OpenACC for use with GPU architectures. This version is derived from the OpenMP 4.5 implementation. You will likely need to modify the Makefile to supply the appropriate compiler and compiler flags.
+
 ## Compilation
 
 To compile XSBench with default settings, navigate to your selected source directory and use the following command: