Add an example at the end of usage, and extend help for -o option (Fix issue #96)

testing/chameleon_ztesting.c

@@ -49,8 +49,8 @@ static parameter_t parameters[] = {
     { "Q",       "Columns (Q) in the PxQ process grid", 'Q', PARAM_OUTPUT,                1, 2, TestValInt, { 1}, NULL, pread_int, sprint_int },
 
     { NULL, "Main input parameters", 0, PARAM_OPTION, 0, 0, 0, {0}, NULL, NULL, NULL },
-    { "op",   "Operation to test/time", 'o', PARAM_OPTION | PARAM_OUTPUT, 1, 1, TestString, {0}, NULL, pread_string, sprint_string },
-    { "file", "Input file",             'f', PARAM_OPTION,                1, 1, TestString, {0}, NULL, pread_string, sprint_string },
+    { "op",   "Operation to test/time ('-o help' to get the list of functions)", 'o', PARAM_OPTION | PARAM_OUTPUT, 1, 1, TestString, {0}, NULL, pread_string, sprint_string },
+    { "file", "Input file",                                                      'f', PARAM_OPTION,                1, 1, TestString, {0}, NULL, pread_string, sprint_string },
 
     { NULL, "Matrix definition parameters", 0, PARAM_OPTION, 0, 0, 0, {0}, NULL, NULL, NULL },
     { "m",    "Dimension M of the operation",    'm', PARAM_OPTION | PARAM_INPUT | PARAM_OUTPUT, 2, 5, TestValInt, {0}, NULL, pread_int, sprint_int },
@@ -160,7 +160,11 @@ void print_usage( const char* prog_name )
                     str, param->helper );
         }
 
-        printf( "\n" );
+        printf( "\n"
+                "For example: %s -H -o gemm -t 2 -m 2000 -n 2000 -k 2000 -b 200\n"
+                "  will run one gemm with three matrices of size 2000x2000 each and a tile size of 200.\n"
+                "  The output will be in the human readable format\n"
+                "\n", prog_name );
     }
 }