Add repos for EL 9 in updating guide

[AkshayGadhaveRH]

Since the latest version is supported on both EL8 and EL9, the repos for EL9 too need to be mentioned in the updating guide.

JIRA: https://issues.redhat.com/browse/SAT-28824

What changes are you introducing?

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

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

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:

• [X] Foreman 3.12/Katello 4.14 (Satellite 6.16)
• [ ] Foreman 3.11/Katello 4.13
• [ ] Foreman 3.10/Katello 4.12
• [ ] 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 6c014d290dfe8aea145779b9882bbd21f4adbbf2 is available at theforeman-foreman-documentation-preview-pr-3378.surge.sh

The following output files are affected by this PR:

• Updating_Project/index-satellite.html

show diff

show diff as HTML

[evgeni]

Will you do the disconnected part in this PR, or separate one?

ACK on the connected parts :)

[AkshayGadhaveRH]

@evgeni I'll do it in this PR itself.

[AkshayGadhaveRH]

@evgeni edited disconnected guide as well. Does this look good?

[evgeni]

LGTM besides the formatting thing

[AkshayGadhaveRH]

@asteflova is this good to be merged?

[asteflova]

Merged to "master" and cherry-picked:

• 8e5c3ae1f3..1e706f6cff 3.12 -> 3.12