Resolve FIXME and use correct GH nickname

Author: max-svistunov

SUPPORT.md

@@ -1,6 +1,6 @@
 # Reporting bugs
 
-* **External contributors**: Open a [GitHub Issue](https://github.com/lightspeed-core/lightspeed-stack/issues/new?template=bug_report.md) using the bug report template. For urgent issues, tag <!-- FIXME: is it fine @ptisnovs to tag you like this? --> in the issue.
+* **External contributors**: Open a [GitHub Issue](https://github.com/lightspeed-core/lightspeed-stack/issues/new?template=bug_report.md) using the bug report template. For urgent issues, tag @tisnik in the issue.
 * **Red Hat contributors**: File a bug in [Jira](https://issues.redhat.com) under the Lightspeed Core (LCORE) project. For urgent issues, ping `@ls-core-team` on Slack in the `#forum-lightspeed` channel.
 
 In both cases, include: steps to reproduce, expected vs. actual behavior, and the Lightspeed Stack version.