docs: add IMAGE_DIGEST_* as well to *.tag docs examples

[aaron-prindle]

fixes #8400

[codecov]

Codecov Report

Merging #8402 (c94ed09) into main (290280e) will decrease coverage by 4.60%.
The diff coverage is 54.85%.

@@            Coverage Diff             @@
##             main    #8402      +/-   ##
==========================================
- Coverage   70.48%   65.89%   -4.60%     
==========================================
  Files         515      605      +90     
  Lines       23150    29819    +6669     
==========================================
+ Hits        16317    19648    +3331     
- Misses       5776     8697    +2921     
- Partials     1057     1474     +417     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/completion.go	13.04% <0.00%> (-1.25%)	⬇️
cmd/skaffold/app/cmd/config/list.go	65.21% <ø> (ø)
cmd/skaffold/app/cmd/config/set.go	88.72% <ø> (ø)
cmd/skaffold/app/cmd/config/util.go	54.28% <ø> (ø)
cmd/skaffold/app/cmd/credits.go	100.00% <ø> (ø)
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/generate_pipeline.go	60.00% <ø> (ø)
cmd/skaffold/app/cmd/inspect_modules.go	65.00% <ø> (ø)
cmd/skaffold/app/cmd/inspect_profiles.go	66.66% <ø> (ø)
... and 415 more

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[gsquared94]

LGTM.