Remove 'Optional:' from heading

[aneta-petrova]

What changes are you introducing?

Removing the keyword "Optional:" from a heading and moving it to the abstract.

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

It seems that the element is causing an older downstream Satellite version. I'd like to change it in all versions for consistency.

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

Contributor checklists

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

Please cherry-pick my commits into:

• Foreman 3.16/Katello 4.18 (Satellite 6.18)
• Foreman 3.15/Katello 4.17
• Foreman 3.14/Katello 4.16 (Satellite 6.17; orcharhino 7.4)
• Foreman 3.13/Katello 4.15 (EL9 only)
• Foreman 3.12/Katello 4.14 (Satellite 6.16; orcharhino 7.2 on EL9 only; orcharhino 7.3)
• Foreman 3.11/Katello 4.13 (orcharhino 6.11 on EL8 only; orcharhino 7.0 on EL8+EL9; orcharhino 7.1 with Leapp)
• Foreman 3.10/Katello 4.12
• Foreman 3.9/Katello 4.11 (Satellite 6.15; orcharhino 6.8/6.9/6.10)
• We do not accept PRs for Foreman older than 3.9.

[github-actions]

The PR preview for 9984db6 is available at theforeman-foreman-documentation-preview-pr-4320.surge.sh

The following output files are affected by this PR:

• Configuring_User_Authentication/index-foreman-el.html
• Configuring_User_Authentication/index-katello.html
• Configuring_User_Authentication/index-orcharhino.html
• Configuring_User_Authentication/index-satellite.html

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show diff as HTML

[apinnick]

LGTM

[aneta-petrova]

Merged to "master" and cherry-picked:

e09806b..d7f6a7d 3.12 -> 3.12
99b40ad..692d460 3.13 -> 3.13
e78993c..8b7cb15 3.14 -> 3.14 (cherry-picked from 3.15)
a480b21..1228c5e 3.15 -> 3.15 (minor conflict)
f31c50c..6e638aa 3.16 -> 3.16