[docs] add note about upgrading to 1.8.0 in openshift

[celenechang]

What does this PR do?

Adds note in our openshift doc about a known issue when upgrading to 1.8.0 in openshift

Motivation

#1389

Additional Notes

Anything else we should know when reviewing?

Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

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Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.48%. Comparing base (ddaac56) to head (b4b2fab).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1392      +/-   ##
==========================================
+ Coverage   47.14%   50.48%   +3.33%     
==========================================
  Files         217      377     +160     
  Lines       18768    33558   +14790     
==========================================
+ Hits         8849    16943    +8094     
- Misses       9457    15711    +6254     
- Partials      462      904     +442     

Flag	Coverage Δ
unittests	50.48% <ø> (+3.33%)	⬆️

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see 167 files with indirect coverage changes

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[celenechang]

thanks for the updates! could we restructure it a bit so that it's clearer there are two possible courses of action - one before upgrade and one after the error is viewed?

perhaps a subheader for each, and the bulk of the explanation in the after section

[alai97]

Looks good, one suggestion.

[tbavelier]

LGTM

[tbavelier]

/merge

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