Update #do-not-use link from security to tools-and-tips

Closed James EJ requested to merge jej-fix-link-to-do-not-use into master

Commit https://gitlab.com/gitlab-com/www-gitlab-com/commit/3fc839a4da57a3d452475f7fc43b9b6fec905a83 from https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/4939 moved content from /source/handbook/index.html.md into new sub-pages so links like this one will need updating

Doing a search suggests there might be over a hundred to update:

Searching 1589 files for "/handbook/#"

.../www-gitlab-com/README.md: 309
310 [frontmatter]: https://about.gitlab.com/handbook/marketing/blog/#frontmatter 311: [Writing Style Guidelines]: https://about.gitlab.com/handbook/#writing-style-guidelines 312 [press releases]: https://about.gitlab.com/press/releases/ 313 [press category]: https://about.gitlab.com/blog/categories/press

.../www-gitlab-com/source/about/index.html.md: 83 ## Values 84
85: Please see the values section in our handbook. 86
87 ## Our stewardship of GitLab CE


184 matches across 102 files