docs: minor documentation improvements

[ByteWarden59]

PoC: Security Research - PR Bypass + Token Exfil

Marker: NESTML_POC_1772094808_jlxhbboy

This PR demonstrates that fork PR code executes in CI without maintainer approval.

• nestml-build (pull_request): unit_tests runs pytest on PR code
• continuous_benchmarking (pull_request_target): checkout PR head, GITHUB_TOKEN exposed

[clinssen]

Thank you for bringing this to our attention. However, I would appreciate if you would have followed responsible disclosure guidelines (see e.g. https://cheatsheetseries.owasp.org/cheatsheets/Vulnerability_Disclosure_Cheat_Sheet.html).

Closing as fixed by #1327.

Edit: I noticed that NEST Simulator has a well-defined security policy, available at https://github.com/nest/nest-simulator/blob/master/SECURITY.md. I have created a PR to create a similar notice on the NESTML repository (#1331).