Updates landing page and conf.yaml to specify Elastic Stack 8.19 and earlier

[KOTungseth]

Updates the /guide landing page to specify the Elastic Stack 8.19 and earlier.

Adds SEO title and description meta data to specify the Elastic Stack 8.19 and earlier.

[github-actions]

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[Copilot]

Pull Request Overview

Updates documentation landing page and configuration to clarify that this documentation covers Elastic Stack 8.19 and earlier versions, providing clear navigation guidance to users seeking current documentation.

• Replaces generic "previous version" warning with specific version information (8.19 and earlier)
• Adds SEO metadata specifying the version scope in page title and description
• Updates user messaging to reference latest versions (Stack 9.1.0 and Cloud Serverless)

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
extra/docs_landing.html	Updates landing page banner to specify Elastic Stack 8.19 and earlier with improved messaging
conf.yaml	Adds SEO metadata with version-specific page title and description

[Copilot]

The hardcoded version references (Stack 9.1.0) in the user message may become outdated quickly. Consider using a more generic reference like 'latest versions' or making this configurable.

Suggested change

	To view the docs for the latest Elastic product versions, including Elastic Stack 9.1.0 and Elastic Cloud Serverless,
	To view the docs for the latest Elastic product versions, including the latest Elastic Stack and Elastic Cloud Serverless,