ug: offline-update: Update doc with more info on app fetching config

[mike-sul]

PR Template and Checklist

Please complete as much as possible to speed up the reviewing process.

Readiness and adding reviewers as appropriate is required.

All PRs should be reviewed by a technical writer/documentation team and a peer. If effecting customers—which is a majority of content changes—a member of Customer Success must also review.

Readiness

• [ ] Merge (pending reviews)
• [ ] Merge after date or event
• [ ] Draft

Overview

Why merge this PR? What does it solve?

Checklist

• [x] Run spelling and grammar check, preferably with linter.
• [ ] Avoid changing any header associated with a link/reference.
• [ ] Step through instructions (or ask someone to do so).
• [ ] Review for wordiness
• [ ] Match tone and style of page/section.
• [ ] Run make linkcheck.
• [ ] View HTML in a browser to check rendering.
• [ ] Use semantic newlines.
• [ ] follow best practices for commits.
  • [ ] Descriptive title written in the imperative.
  • [ ] Include brief overview of QA steps taken.
  • [ ] Mention any related issues numbers.
  • [ ] End message with sign off/DCO line (-s, --signoff).
  • [ ] Sign commit with your gpg key (-S, --gpg-sign).
  • [ ] Squash commits if needed.
• [ ] Request PR review by a technical writer and at least one peer.

Comments

Any thing else that a maintainer/reviewer should know. This could include potential issues, rational for approach, etc.

[doanac]

Docs for c64f12c1792832c58fe838dcb53038f15ee5c3f3 are browsable at: https://ci.foundries.io/projects/fio-docs/builds/2657/docs/artifacts/html/index.html