[DOCS IA] Create Cloud security getting started guide

[benironside]

What can we change to make the docs better?

Our getting started section is sparse on content. We should flesh it out by considering adding links to other guides that explain Elastic security, similar to how the Observability docs getting started page introduces several other getting started guides.

Let's try to identify any additional guides that would be useful for a new user, and link them here.

Doc URL

Please include the doc URL and any other related information where applicable:
Doc URL: https://www.elastic.co/guide/en/security/current/getting-started.html

Which documentation set needs improvement?

ESS only

Software version

[bmorelli25]

cc @jmikell821 perhaps something you and Ben can collaborate on.