docs: add a direct link to create an issue for Infrasec

What

Adding a direct link to make it easy for Team Members to create an issue on the Infrasec issue board.

Why

Team members don't know how to find someone from Infrasec to do this review. Sometimes they send a message on the #security-infrasec slack channel and we create an issue to triage. Other times they are tagging someone from the team and the request goes unanswered:confused:.

With this change, we expect to make this process more explicit.

These issues are prioritized during our weekly sync.

Related slack conversation: https://gitlab.slack.com/archives/C01UZTPDGCB/p1678102489609499