Update docs links of SaaS User Caps

What does this MR do and why?

Relates to #344465 (closed)

Update the links to the docs on User Caps banner, and User Caps settings

Screenshots or screen recordings

SaaS User Caps banner

SaaS User Caps Settings

How to set up and validate locally

SaaS User Caps banner

1. Set Gitlab.com? to return true by changing lib/gitlab.rb
2. Enable saas_user_caps feature flag from rails console. (rails console then Feature.enable(:saas_user_caps))
3. With a group with an Ultimate plan
4. Navigate to Settings -> Permissions, LFS, 2FA -> User Cap
5. Set the user cap limit to 1
6. Navigate to the group members
7. Add one or more members (until you are above the user cap limit set in previous step)
8. Navigate to any page in your group, or the group projects
9. You should see an alert that you have pending members
10. The links should be directing to the new content added in !77567 (merged)

SaaS User Caps Settings

1. Set Gitlab.com? to return true by changing lib/gitlab.rb
2. Enable saas_user_caps feature flag from rails console. (rails console then Feature.enable(:saas_user_caps))
3. With a group with an Ultimate plan
4. Navigate to Settings -> Permissions, LFS, 2FA -> User Cap
5. In the User cap field, the link for "approved by an owner" should point to the new content added in !77567 (merged)

MR acceptance checklist

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