docs: manual rolebindings for global namespaces

[fykaa]

closes #2834

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.90%. Comparing base (aa66473) to head (f100b88).
Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2934      +/-   ##
==========================================
+ Coverage   49.97%   50.90%   +0.93%     
==========================================
  Files         276      279       +3     
  Lines       24811    25178     +367     
==========================================
+ Hits        12400    12818     +418     
+ Misses      11724    11669      -55     
- Partials      687      691       +4     

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[krancour]

I agree with the changes to uppercase here, but probably wouldn't monospace here.

Suggested change

	To manage the progression of `Freight` from `Stage` to `Stage`, Kargo will often
	To manage the progression of Freight from Stage to Stage, Kargo will often

[fykaa]

I see

[fykaa]

There is a Caution text right in the end of Global credentials section, It should give an implication of warning for enabling cluster-wide secrets