Replace xref with link for template sync reference

[asteflova]

What changes are you introducing?

I'm replacing an xref to a Template Sync reference module in Managing Hosts with an external link to a Template Sync reference module in Administering Project. The module the xref points to was removed in https://github.com/theforeman/foreman-documentation/pull/3397.

Why are you introducing these changes? (Explanation, links to references, issues, etc.)

https://github.com/theforeman/foreman-documentation/pull/3397 broke things on 3.11, 3.10, and 3.9 because the affected assembly exists in a different guide there so the xref that works on 3.12 and later doesn't work on 3.11 and earlier.

Anything else to add? (Considerations, potential downsides, alternative solutions you have explored, etc.)

An alternative is to revert https://github.com/theforeman/foreman-documentation/pull/3397 on the broken branches.

Checklists

• [x] I am okay with my commits getting squashed when you merge this PR.
• [x] I am familiar with the contributing guidelines.

Please cherry-pick my commits into:

• [ ] Foreman 3.12/Katello 4.14 (Satellite 6.16)
• [ ] Foreman 3.11/Katello 4.13
• [x] Foreman 3.10/Katello 4.12
• [x] Foreman 3.9/Katello 4.11 (Satellite 6.15; orcharhino 6.8/6.9/6.10)
• [ ] Foreman 3.8/Katello 4.10
• [ ] Foreman 3.7/Katello 4.9 (Satellite 6.14)
• [ ] Foreman 3.6/Katello 4.8
• [ ] Foreman 3.5/Katello 4.7 (Satellite 6.13; orcharhino 6.6/6.7)
• We do not accept PRs for Foreman older than 3.5.

[github-actions[bot]]

The PR preview for fff45f1456e0e70fe74a8f31f9ac25da5642ad06 could not be generated

[ekohl]

fb7bf0a2546a..9a81ebe70a51 3.10 -> 3.10 45e6f7ec9d02..aa43aee93f92 3.9 -> 3.9