Docs: Hint that SELinux can be enabled/disabled

[saschagrunert]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

Add the information that SELinux can be enabled or disabled explicitly.

Which issue(s) this PR fixes:

None

Does this PR have test?

None

Special notes for your reviewer:

None

Does this PR introduce a user-facing change?

Added information that SELinux can be enabled/disabled in `installation-usage.md`.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 41.80%. Comparing base (11d77f4) to head (377db3f).
Report is 243 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2298      +/-   ##
==========================================
- Coverage   45.50%   41.80%   -3.71%     
==========================================
  Files          79      109      +30     
  Lines        7782    15543    +7761     
==========================================
+ Hits         3541     6497    +2956     
- Misses       4099     8570    +4471     
- Partials      142      476     +334     

[pjbgf]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pjbgf, saschagrunert

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