docs: Fix helm command

[jtymes]

Description

Fixes the reference to the helm template --post-renderer command.

[codecov]

Codecov Report

Merging #7987 (c853de4) into main (290280e) will decrease coverage by 3.78%.
The diff coverage is 54.09%.

@@            Coverage Diff             @@
##             main    #7987      +/-   ##
==========================================
- Coverage   70.48%   66.70%   -3.79%     
==========================================
  Files         515      596      +81     
  Lines       23150    28889    +5739     
==========================================
+ Hits        16317    19270    +2953     
- Misses       5776     8195    +2419     
- Partials     1057     1424     +367     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/credits/export.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/deploy.go	40.90% <0.00%> (-12.94%)	⬇️
cmd/skaffold/app/cmd/test.go	44.44% <0.00%> (ø)
cmd/skaffold/app/exitcode.go	100.00% <ø> (+6.66%)	⬆️
cmd/skaffold/skaffold.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/inspect_tests.go	62.50% <14.28%> (-1.14%)	⬇️
cmd/skaffold/app/cmd/render.go	35.48% <18.18%> (-5.90%)	⬇️
cmd/skaffold/app/cmd/lsp.go	28.12% <28.12%> (ø)
cmd/skaffold/app/cmd/run.go	64.28% <33.33%> (-9.63%)	⬇️
cmd/skaffold/app/cmd/fix.go	56.41% <37.50%> (-20.07%)	⬇️
... and 390 more

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