Revise SECURITY.md for version support and reporting

Updated security policy to reflect supported versions and reporting guidelines.

Author: mattn

SECURITY.md

@@ -0,0 +1,33 @@
+# Security Policy
+
+## Supported Versions
+
+Only the latest release on the `v1.14.x` line receives security fixes.
+
+| Version  | Supported          |
+| -------- | ------------------ |
+| 1.14.x   | :white_check_mark: |
+| < 1.14   | :x:                |
+
+## Scope
+
+`go-sqlite3` is a CGo binding that bundles the SQLite amalgamation
+(`sqlite3-binding.c` / `sqlite3-binding.h`). Please report issues to the
+appropriate project:
+
+- Bugs in the Go binding layer, CGo glue, build tags, or this repository's
+  own code: report here.
+- Vulnerabilities in SQLite itself: please report them upstream to the
+  SQLite developers at <https://www.sqlite.org/>. Once a fix is released
+  upstream, this repository will update the bundled amalgamation.
+
+## Reporting a Vulnerability
+
+Please **do not** open a public GitHub issue for security problems.
+
+Use GitHub's private vulnerability reporting:
+<https://github.com/mattn/go-sqlite3/security/advisories/new>
+
+This project is maintained on a best-effort basis by volunteers, so please
+allow reasonable time for investigation and a fix before any public
+d