Update SECURITY.md (#2255)

* Update SECURITY.md

- Link PR for per-transport SSL
- Mark Jetty using upstream config as [Done]

* Update SECURITY.md

- Add 6.3.x as security supported release

Author: mattrpav

SECURITY.md

@@ -4,6 +4,7 @@
 
 | Version | Supported          | Note |
 | ------- | ------------------ | ---- |
+| 6.3.x   | :white_check_mark: |      |
 | 6.2.x   | :white_check_mark: |      |
 | 6.1.x   | :x: | |
 | 6.0.x   | :x: | | 
@@ -73,9 +74,9 @@ The Apache ActiveMQ team has initiated a security hardening project to move from
 
 1. Enhancements to the SSL authentication plugin to fix wantAuth mode
 
-2. Updates to SSL handling to allow configuring per-transport and per-network connector SSL keys
+2. [#2133] Updates to SSL handling to allow configuring per-transport and per-network connector SSL keys
 
-3. Refactoring of Jetty service to use Jetty-provided configurations instead of Spring-style configuration for Jetty service used by API and web console.
+3. [Done] Refactoring of Jetty service to use Jetty-provided configurations instead of Spring-style configuration for Jetty service used by API and web console.
 
 4. [Done] Limiting XBean URI schemes