update readme

Readme.md

@@ -7,9 +7,15 @@ git clone https://muhq.space/software/allocbench.git
 
 ## Usage
 
+	usage: bench.py [-h] [-s] [-l] [-r RUNS] [-v] [-b BENCHMARKS [BENCHMARKS ...]]
+
+	benchmark memory allocators
+
 	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
+	  -b BENCHMARKS [BENCHMARKS ...], --benchmarks BENCHMARKS [BENCHMARKS ...]
+	                        benchmarks to run