Update README for tests/workload directory tests

tests/workload/README.txt

-1- To run the test use:
+=========================
+== codes-workload-test ==
+=========================
+
+To run the test use:
 
 mpirun -np 4 ./codes-workload-test --sync=2 codes-workload-test.conf
 
-2- To modify the codes-workload-test.conf file, change the 'workload_type' parameters. If using bgp_io_workload type, change the io_kernel_meta_path and bgp_config_file parameters according to your local path.
+===============================
+== codes-workload-mpi-replay ==
+===============================
+
+To run this test use:
+
+mpirun -np NUM_PROCS ./codes-workload-mpi-replay --conf <conf_file_path> --test-dir <test_directory>
+
+- <conf_file_path> is the path of the configuration file to use for this workload replay
+    - this configuration file format is described at the end of this README
+- <test_directory> is the directory to replay the actual i/o operations in
+    - TODO: the replay tool does not currently replay workloads that do not create the files they
+            do i/o to (you can generate verbose i/o output, but not actually replay the i/o)
+
+The following options may be specified on the command line:
+
+-noop : do not perform i/o
+-v : verbose output of i/o details/parameters
+
+NOTE: NUM_PROCS need not match the number of ranks in the actual workload. I.E. if the workload is a
+      darshan log with 1024 ranks, and NUM_PROCS is set to 8, i/o events will just be generated for
+      ranks 0-7. This should not cause any runtime errors.
+
+==============================
+== codes-workload-test.conf ==
+==============================
+
+This file contains the sample configuration for each of the 3 (current) workload generators: test
+workload generator, bgp i/o language workload generator, and the darshan i/o workload_generator.
+These configuration files are passed as arguments to both the codes-workload-test and the
+codes-workload-mpi-replay programs. A summary of each workloads parameters is given below (NOTE:
+these parameters should be updated each time a new paramter is added to each workload):
+
+1.) test workload generator:
+
+PARAMS
+{
+    workload_type = "test";
+}
+
+- workload_type is just the name of this generator ("test")
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+2.) bgp i/o language workload generator:
+
+PARAMS
+{
+    workload_type = "bgp_io_workload";
+    io_kernel_meta_path = "/path/to/io/kernel/meta.txt";
+    bgp_config_file = "/path/to/bgp/config/file.txt";
+    rank_count = "8";
+}
+
+- workload_type is just the name of this generator ("bgp_io_workload")
+- io_kernel_meta_path is the path to the i/o kernel meta file
+- bgp_config_file is the path to the bgp config file
+- rank_count is the number of ranks to generate i/o for
+    - this needs to match the range of ranks given in the io_kernel_meta_file
+    - this also needs to match the num_cn value in the bgp_config_file
+        - NOTE: num_ion should be set so there is 1 ion for every 64 cns
+        - NOTE: num_fileserver and num_es must be 64 or 123 (half or full storage system)
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+3.) darshan i/o workload generator:
+
+PARAMS
+{
+    workload_type = "darshan_io_workload";
+    log_file_path = "/path/to/darshan/log";
+    aggregator_count = "18";
+}
 
-3- Currently, the bgp_io_workload type only loads the workload file. TODO: read the operations inside the workload file one by one, load the appropriate parameters and display them correctly.
+- workload_type is just the name of this generator ("darshan_io_workload")
+- log_file_path is the path to the darshan log to generate i/o for
+- aggregator_count is the number of collective aggregators to use for collective file i/o generation
+    - NOTE: this value may have a strong impact on the generated i/o pattern
+            - i.e. if it is not known, it may be very difficult to reproduce the original pattern
+    - NOTE: this value can be set to anything if the workload is mostly independently opened files