changes security.md to the required format

Author: HARSHVARANDANI

SECURITY.md

@@ -1,6 +1,9 @@
 # Security Policy
 
-This project follows the security policy used by rust-lightning.
+## Reporting a Vulnerability
 
-See:
-https://github.com/lightningdevkit/rust-lightning/blob/main/SECURITY.md
+Security vulnerabilities for `ldk-server` are handled under the same policy as
+`rust-lightning`(LDK), on which this library is built.
+
+Please refer to the [rust-lightning's SECURITY.md](https://github.com/lightningdevkit/rust-lightning/blob/main/SECURITY.md)
+for instructions on how to responsibly disclose vulnerabilities.