doc: fix anchor links in and to glossary

[iFreilicht]

Motivation

Some links in the glossary and nix-store help are broken.

The links in the nix-store help still link to the glossary, but their anchor name is wrong, so you only land at the top of the page.

Context

Trivial change, only small docs changes with no potential side-effects.

Checklist for maintainers

Maintainers: tick if completed or explain if not relevant

• agreed on idea
• agreed on implementation strategy
• tests, as appropriate
  • functional tests - tests/**.sh
  • unit tests - src/*/tests
  • integration tests
• documentation in the manual
• code and comments are self-explanatory
• commit message explains why the change was made
• new feature or bug fix: updated release notes