docs: update changelog for v2.8.0

[renzodavid9]

Changelog and schema changes for v2.8.0

[codecov]

Codecov Report

Merging #9109 (146b358) into main (290280e) will decrease coverage by 7.08%.
Report is 1035 commits behind head on main.
The diff coverage is 48.33%.

@@            Coverage Diff             @@
##             main    #9109      +/-   ##
==========================================
- Coverage   70.48%   63.41%   -7.08%     
==========================================
  Files         515      628     +113     
  Lines       23150    32331    +9181     
==========================================
+ Hits        16317    20502    +4185     
- Misses       5776    10265    +4489     
- Partials     1057     1564     +507     

Files	Coverage Δ
cmd/skaffold/app/cmd/commands.go	97.61% <100.00%> (+0.35%)	⬆️
cmd/skaffold/app/cmd/config.go	100.00% <100.00%> (ø)
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/debug.go	100.00% <100.00%> (ø)
cmd/skaffold/app/cmd/flags.go	93.00% <100.00%> (+2.18%)	⬆️
cmd/skaffold/app/cmd/generate_pipeline.go	60.00% <ø> (ø)
cmd/skaffold/app/cmd/init.go	100.00% <100.00%> (ø)
... and 41 more

... and 432 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[renzodavid9]

Failing test is a known problem: when we do an schema upgrade the test fails due to it expects the examples to have the schema version from the latest version found in GCS, which doesn't correspond to the version we want to launch