Update existing cumulative docs contributing guidelines

[colleenmcginnis]

Related to elastic/docs-builder#2135 and elastic/docs-builder#2322 and

Summary

• Update existing cumulative docs contributing guidelines
• Add examples that include ranges
• Update get started content as needed

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

cc @florent-leborgne @vishaangelova @shainaraskas

[github-actions]

Vale Linting Results

Summary: 4 suggestions found

💡 Suggestions (4)

File	Line	Rule	Message
contribute-docs/how-to/cumulative-docs/example-scenarios.md	285	Elastic.WordChoice	Consider using 'refer to (if it's a document), view (if it's a UI element)' instead of 'see', unless the term is in the UI.
contribute-docs/how-to/cumulative-docs/example-scenarios.md	618	Elastic.EmDashes	Don't put a space before or after a dash.
contribute-docs/how-to/cumulative-docs/example-scenarios.md	646	Elastic.Wordiness	Consider using 'because' instead of 'Since'.
contribute-docs/how-to/cumulative-docs/guidelines.md	294	Elastic.Wordiness	Consider using 'impossible' instead of 'not possible'.

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The Vale linter checks documentation changes against the Elastic Docs style guide.

To use Vale locally or report issues, refer to Elastic style guide for Vale.

[github-actions]

🔍 Preview links for changed docs

• contribute-docs/how-to/cumulative-docs/badge-placement.md
• contribute-docs/how-to/cumulative-docs/example-scenarios.md
• contribute-docs/how-to/cumulative-docs/guidelines.md
• contribute-docs/how-to/cumulative-docs/index.md
• contribute-docs/locally.md
• contribute-docs/on-the-web.md
• get-started/howto-use-the-docs.md
• get-started/versioning-availability.md

[florent-leborgne]

Thanks @colleenmcginnis, LGTM

[shainaraskas]

didn't spot anything other than what florent called out

there's some debt in how we describe "the schism" that I spotted but I don't think it needs to be addressed in this PR