feat: update readme

README.md

@@ -1,3 +1,26 @@
 # script-sign
 
-Script Sign crate
+Script Sign crate
+
+
+## Signature V1
+
+```text
+@SCRIPT-SIGNATURE-V1: <key-id>.<algorithm>.<time>.<signature-value-in-base64>
+```
+
+## Signature V2
+
+```text
+@SCRIPT-SIGNATURE-V2: <key-id>.[<algorithm>.<time>.<public-key>.<signature1-value-in-base64>].<algorithm>.<time>.<signature2-value-in-base64>
+```
+
+In V2 use new sub signature:
+```plain
+<algorithm>.<time>.<public-key>.<signature1-value-in-base64>
+```
+
+Notice:
+- `<signature1-value-in-base64>` is signed by `<key-id>`
+- `<signature2-value-in-base64>` is signed by `<public-key>`
+