fix(docs): add trainling slashes to doc-links.yaml

[muescha]

Description

changes:

• unify all links and add trailing slash

related issues

• chore(docs): Add Snipcart reference guide #22628 chore(docs): Add Snipcart reference guide
• Feature Request: add test for trailing slashes in yaml files with links #24014 Feature Request: add test for trailing slashes in yaml files with links

[AishaBlake]

Approving this! For future reference, this and #22936 could probably have been a single PR. They're pretty closely related (and were introduced in the same PR).

[muescha]

@AishaBlake

in #22205 (comment) i got the advice that i should split it into smaller packages to make PR easy to check

open tightly-scoped PRs for each chunk of work, such as a section of the tutorial, to make it easier for us to review and test

and i agree it is more easy to check the small scoped chunks instead of a big one - thats why i opened it in separate PRs