Add documentation on use of metadata in data catalog (and with Kedro-Viz)

[AhdraMeraliQB]

Introduction

Viz now processes dataset layer and preview information from the metadata attribute. We should document how users are able to make use of these.

Formatting suggestion

1. Replace the section "Visualise layers" on this page with "Using metadata for added visualisation", or something to that effect. "Visualise layers" then becomes a subsection under that heading, and we introduce the subsection "Preview datasets" with instruction on how to use metadata to enable previews.

2. Add the bullet "Metadata" to https://docs.kedro.org/en/stable/data/data_catalog.html#use-the-data-catalog-within-kedro-configuration, potentially link to the section described in point 1 or the section introduced in kedro-org/kedro#2676 (or both!)