Update README.md

Author: sharkLoc

README.md

@@ -1,2 +1,21 @@
 # bamkit
 bamkit: a simple program for bam file manipulation
+
+
+### usage:
+```
+bamkit: a simple program for bam file manipulation
+
+Usage: bamkit <COMMAND>
+
+Commands:
+  view    sam bam conversion
+  region  get target region from bam file
+  flags   bam file flag value show
+  insert  insert size plot for bam file
+  help    Print this message or the help of the given subcommand(s)
+
+Options:
+  -h, --help     Print help information
+  -V, --version  Print version information
+```