Create SECURITY.md

# Security Policy

## Supported Versions

Use this section to tell people about which versions of your project are
currently being supported with security updates.

| Version | Supported          |
| ------- | ------------------ |
| 5.1.x   | ✅ |
| 5.0.x   | ❌                |
| 4.0.x   | ✅ |
| < 4.0   | ❌                |

## Reporting a Vulnerability

Use this section to tell people how to report a vulnerability.

Tell them where to go, how often they can expect to get an update on a
reported vulnerability, what to expect if the vulnerability is accepted or
declined, etc.

SECURITY.md

@@ -0,0 +1,21 @@
+# Security Policy
+
+## Supported Versions
+
+Use this section to tell people about which versions of your project are
+currently being supported with security updates.
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 5.1.x   | :white_check_mark: |
+| 5.0.x   | :x:                |
+| 4.0.x   | :white_check_mark: |
+| < 4.0   | :x:                |
+
+## Reporting a Vulnerability
+
+Use this section to tell people how to report a vulnerability.
+
+Tell them where to go, how often they can expect to get an update on a
+reported vulnerability, what to expect if the vulnerability is accepted or
+declined, etc.