README: Update.

1 files changed, 17 insertions, 1 deletions

diff --git a/README.md b/README.md
index d22bb8d..18e4ef2 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,19 @@
 # ob-acl2
 
-ob-acl2 is a software to run acl2 on org-babel.
+**THIS CODE IS VERY DANGEROUS. It automatically executes an ACL2 program on the `*shell*` buffer.**
+
+Org-babel functions for ACL2.
+
+# Usage
+
+First, Run ACL2 in `*shell*` buffer of Emacs.
+
+```
+$ acl2
+```
+
+Second, use org-babel.
+
+# LICENSE
+
+See COPYING file.