docs: Include released 10.x and 11.x versions under security policy.
Fixes
| Version | Supported |
| ------- | ------------------ |
+| 11.0.x | :heavy_check_mark: |
+| 10.3.x | :heavy_check_mark: |
+| 10.2.x | :heavy_check_mark: |
+| 10.1.x | :heavy_check_mark: |
| 10.0.x | :heavy_check_mark: |
| 9.1.x | :heavy_check_mark: |
| < 9.1 | :x: |
