update readme

readme.md

@@ -1,12 +1,20 @@
 # cs
 
-calculate checksums
+concurrently calculate/verify checksums (cs)
 
-It's a simpler version of shasum + md5sum, but only for md5, sha1, sha256, and
-sha512.
+It's a simpler version of shasum + md5sum, but concurrently and only with
+support for md5, sha1, sha256, and sha512.
 
 ## usage
 
+    # create checksums
     cs -a 256 < foo.txt
     cs foo.txt
-    cs -a sha1 foo.txt foo.txt foo.txt
+    cs -a sha1 foo.txt foo.txt foo.txt > checksums.sha1
+
+    # verify
+    cat checksums.sha1 | cs -c 
+    cs -c checksums.sha1
+
+    # both
+    cs $(find ~/src/mcquay.me | grep  '\.go$') | cs -c