Add security policy documentation

Author: xterao

SECURITY.md

@@ -0,0 +1,27 @@
+# Security Policy
+We take all security bugs very seriously.
+
+## Supported Versions
+
+The community fixes security bugs in the latest version.
+Depending on the severity of the issue and the age of the release, we may fix vulnerabilities in older versions, but we generally commit fixes only to the latest released version.
+
+Example:
+
+| Current Release | Supported for Security Fixes | Not Supported |
+|:---------------:|:----------------------------:|:-------------:|
+| 2.1             | 2.1                          |   2.x, 1.x    |
+| 3.0             | 3.0                          |   2.x, 1.x    |
+
+*If multiple major versions are maintained in the future, fixes may be applied to each major version.*
+
+Example:
+
+| Current Release | Supported for Security Fixes |    Not Supported     |
+|:---------------:|:----------------------------:|:--------------------:|
+| 2.1             |       2.1 ,latest 1.x        | older 2.x, older 1.x |
+| 3.0             | 3.0 ,latest 2.x, latest 1.x  | older 2.x,older 1.x  |
+
+## Reporting Vulnerabilities
+
+To report a vulnerability, please register an [issue on GitHub](https://github.com/domaframework/doma-tools-for-intellij/issues).