Examples versioning

[r2d4]

Fixes #367
Fixes #1003

The examples are currently integration tested, but against the code at skaffold HEAD. Configuration changes, such as v1alpha2 -> v1alpha3 will be present at HEAD, but not in the latest released version.

When users download the latest skaffold release, the examples are written for v1alpha3, but the latest release only targets v1alpha2 and below. Therefore, the examples will all fail, and users won't be able to skaffold fix, because the old version does not know about the new transformations. (skaffold fix only helps the situation of old config, new skaffold, where this is new config, old skaffold.

We would like to keep our examples integration tested, so that they don't break for users. This PR makes integration/examples the canonical example repository. All changes are synced to examples on each release.

This solves:

• Examples are still integration tested
• Examples are guaranteed to stay in sync with new skaffold changes
• Examples in the examples/ directory are runnable with the latest released version of skaffold

This adds the sync to release_note.sh script, which might not be the best place for it.

[codecov-io]

Codecov Report

Merging #1019 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1019   +/-   ##
=======================================
  Coverage   39.98%   39.98%           
=======================================
  Files          70       70           
  Lines        3079     3079           
=======================================
  Hits         1231     1231           
  Misses       1721     1721           
  Partials      127      127

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[nkubala]

one nit, otherwise LGTM