Change indentation in kea config example

[gene1wood]

Description

This seeks to improve how the example kea dhcp4 config is rendered. This both changes leading tabs to spaces and creates indentation that was missing.

The result is that when rendered on the site, the configurations indentation follows the logical structure of the JSON.

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Change indentation in kea config example

This seeks to improve how the example kea dhcp4 config is rendered. This both changes leading tabs to spaces and creates indentation that was missing.

The result is that when rendered on the site, the configurations indentation follows the logical structure of the JSON.

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Checklist

• I have read and followed the Ubuntu Server contributing guide.
• I have signed the Contributor License Agreement (CLA).
• My pull request is linked to an existing issue (if applicable).
• I have tested my changes, and they work as expected.

[athos-ribeiro]

Thanks! LGTM