docs: add kiwi to README quick-start prerequisites

[Copilot]

The quick start missed kiwi, so users could install azldev successfully but hit a hard failure on azldev image build due to missing tooling. This updates the documented prerequisite install set to match runtime requirements.

• Problem

  • Quick-start dependency list did not include kiwi, while image build prerequisite checks require it.

• Change

  • Updated the README quick-start install command to include kiwi in the prerequisite package list.

• Snippet

  # before
  dnf install -y golang mock dnf-utils mock-rpmautospec
  
  # after
  dnf install -y golang mock dnf-utils mock-rpmautospec kiwi

[Copilot]

Pull request overview

Updates the repository’s primary quick-start documentation to better reflect the host tooling required to successfully run azldev image build, preventing users from getting past installation only to fail later during image builds.

Changes:

• Adds kiwi to the README quick-start prerequisite install command.

[christopherco]

kiwi resolves to kiwi-cli and pulls in dependencies like gdisk