Add Changelog for Katib v0.15.0

[andreyvelich]

I added Changelog for Katib v0.15.0

@kimwnasptd @apo-ger I've added breaking change about Katib authz in this release.
Please let me know if that sounds good.

/assign @gaocegege @johnugeorge @tenzen-y @elenzio9 @kimwnasptd @apo-ger

[tenzen-y]

Thank you for the updates!
/lgtm
/hold for other reviewers

[andreyvelich]

/cc @anencore94 @orfeas-k @d-gol @shaowei-su @zhixian82 @fischor @keisuke-umezawa

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[andreyvelich]

cc @jbottum for visibility.

[johnugeorge]

/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andreyvelich, johnugeorge

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[johnugeorge]

/hold cancel