Security handbook fixes (1password related)

Concerns: Handbook - Security Practices

There were a few things that I thought were confusing while working through the 1password setup, so I thought I'd send an MR with some proposals for improvement. All changes are made to the 1password section only. Here's what I did:

• fix: broken intra-page link
• cosmetic: drop a repeated word
• cosmetic: update vault selector screenshot (it said "Shared" which confused me, since the text is talking about a "Team" vault, and that's what I ended up getting access to); I also dropped the name to remove personal references
• proposal: I changed the wording around connecting vaults, since it sounded as if the Team vault becomes available straight away, which caused confusion in my onboarding issue. I therefore changed the wording to point out that access to this is granted separately, so there may be a delay. I think for me it was my manager who added me to it afterwards.

I lumped these changes together in a single MR because they all seemed pretty minor. I created separate commits in case you'd want me to revert only some.

Side note: this is my second day at GitLab, apologies if I missed anything about following a certain MR format etc. (I checked the templates and README but there doesn't seem to be a template for handbook MRs.) Feel free to point out anything I could have done better! 🙏🏻