Create SECURITY.md (#3288)

* Create SECURITY.md

* Update SECURITY.md

Remove boiler plate text

Author: FatherShawn

SECURITY.md

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+# Security Policy
+
+## Supported Versions
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 2.x     | :white_check_mark: |
+| 1.9.x   | :white_check_mark: |
+| < 1.9   | :x:                |
+
+## Reporting a Vulnerability
+
+If you think you've found a vulnerability, please use the _Report a vulnerability_ button found in the [security tab](https://github.com/bigskysoftware/htmx/security) of the project on Github.
+
+This process is documented in GitHub's _Secure Coding_ guide: [Privately reporting a security vulnerability](https://docs.github.com/en/code-security/security-advisories/guidance-on-reporting-and-writing-information-about-vulnerabilities/privately-reporting-a-security-vulnerability#privately-reporting-a-security-vulnerability).