Flesh out 'Deploy', sidequest to update 'Get Started'

[leemthompo]

Closes https://github.com/elastic/docs-projects/issues/334

get-started/

1. index.md: Major overhaul - Simplified to focus on first steps for users, with clear pathways to learn about Elasticsearch, Kibana, solutions, deployment options, and versioning. Clears out duplication as much possible.

2. introduction.md: Significant restructuring - Combined Elasticsearch and Kibana overview into a single comprehensive overview, explaining what they are and their use cases. Lots of $$$ to clean up eventually on this page.

3. the-stack.md: Streamlined - Made more concise and added clearer deployment options references.

4. versioning-availability.md: New file - Added detailed explanation of:

   • Semantic versioning (X.Y.Z format)
   • Feature availability states (GA, Beta, Preview, etc.)
   • Deployment type variations

5. deployment-options.md: Simplified to serve as a quick reference for deployment options, using content reuse outlined below.

6. Removed: installing-elastic-stack.md - anchors moved to deploy-manage section for redirection

deploy-manage/

1. deploy.md: New comprehensive deployment guide including:

   • Core components overview
   • Detailed deployment options
   • Version compatibility considerations
   • Decision framework for choosing deployment type
   • Cost considerations

2. New snippet file _snippets/deployment-options-overview.md: Created to maintain consistent deployment options documentation across multiple pages, including:

   • Quick start option (Local development)
   • Hosted options (Cloud Hosted and Serverless)
   • Advanced options (Self-managed, Cloud Enterprise, Cloud on K8s)

[florent-leborgne]

Nice!! Can you change the link to "Kibana" at the end of the-stack.md to point to explore-analyze/index.md?

[karenzone]

Thanks for your work on this. Left comments inline.

GLOBAL:

• Use present tense
• Use attributes when available

Otherwise, LGTM

[florent-leborgne]

This reads well as an intro and has the right entry points, nice! Some minor/open questions