Update security reporting instructions in SECURITY.md

Overarching issue for all thingweb repositories to use the new Eclipse template from https://github.com/eclipse-csi/security-handbook/blob/main/templates/SECURITY.md

* [x] [.eclipsefdn](https://github.com/eclipse-thingweb/.eclipsefdn) (not needed)
* [ ] [.github](https://github.com/eclipse-thingweb/.github) (present and delete), see https://github.com/eclipse-thingweb/.github/pull/11
* [x] [dart_wot](https://github.com/eclipse-thingweb/dart_wot) (misses SECURITY.md currently)
* [x] [domus-tdd-api](https://github.com/eclipse-thingweb/domus-tdd-api)
* [x] [examples](https://github.com/eclipse-thingweb/examples) needed ???
* [x] [infrastructure](https://github.com/eclipse-thingweb/infrastructure) needed ???
* [ ] [kotlin-wot](https://github.com/eclipse-thingweb/kotlin-wot) (misses SECURITY.md currently)
* [x] [node-red](https://github.com/eclipse-thingweb/node-red) (misses SECURITY.md currently)
* [x] [node-wot](https://github.com/eclipse-thingweb/node-wot), see https://github.com/eclipse-thingweb/node-wot/pull/1547
* [x] [playground](https://github.com/eclipse-thingweb/playground), see https://github.com/eclipse-thingweb/playground/pull/763
* [x] [td-code](https://github.com/eclipse-thingweb/td-code) (misses SECURITY.md currently)
* [x] [td-tools](https://github.com/eclipse-thingweb/td-tools) (misses SECURITY.md currently), see https://github.com/eclipse-thingweb/td-tools/pull/88
* [x] [test-things](https://github.com/eclipse-thingweb/test-things) (misses SECURITY.md currently), see https://github.com/eclipse-thingweb/test-things/pull/86
* [ ] [thingweb](https://github.com/eclipse-thingweb/thingweb) (not needed?)
* [x] [ui-wot](https://github.com/eclipse-thingweb/ui-wot)
* [x] [wam](https://github.com/eclipse-thingweb/wam) (misses SECURITY.md currently)
* [ ] [wotpy](https://github.com/eclipse-thingweb/wotpy) (misses SECURITY.md currently)