add Usage to output

Readme.md

@@ -7,4 +7,9 @@ git clone https://muhq.space/software/allocbench.git
 
 ## Usage
 
-
+    optional arguments:
+      -h, --help            show this help message and exit
+      -s, --save            save benchmark results to disk
+      -l, --load            load benchmark results from disk
+      -r RUNS, --runs RUNS  how often the benchmarks run
+      -v, --verbose         more output