removes an outdated reference to Node Security Project, which was acquired by npm some time ago. The new workflow for the same process (now the npm advisories page) has been added.

cc @electron/wg-security

Description of Change

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.
• This is NOT A BREAKING CHANGE. Breaking changes may not be merged to master until 11-x-y is branched.

Release Notes

Notes: none