Document update process for Docker deployments

[toby-sutor]

Add a section that describes on how to update Elasticsearch when running on Docker. Should probably be reviewed.

Source:

• https://discuss.elastic.co/t/how-to-upgrade-elasticsearch-in-docker-compose-yml/301408/2
• https://discuss.elastic.co/t/how-to-properly-upgrade-elasticsearch-running-as-docker-containers/221711/2
• https://discuss.elastic.co/t/upgrade-elk-on-docker-from-7-10-to-7-17/312839/6

[github-actions[bot]]

Documentation preview:

• ✨ Changed pages

[elasticsearchmachine]

@toby-sutor please enable the option "Allow edits and access to secrets by maintainers" on your PR. For more information, see the documentation.

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)

[leemthompo]

[!IMPORTANT]
Elastic documentation is migrating to Markdown for version 9.0+. See the migration guide for details.

ℹ️ What's happening?

• Starting January 29, we will start closing all unmerged documentation PRs targeting main/master
• We're migrating from AsciiDoc to Markdown for 9.0+
• 9.0 docs will be frozen from January 29 until February 20 2024
• NOTE: PRs that include both code and documentation changes will remain open

What do I need to do?

For <=8.x docs:

1. Rebase your PR to target the relevant 8.x branch instead
2. The content can remain in AsciiDoc format

For 9.0+ docs:

Option 1:

• Draft docs in Markdown
• Once migration freeze ends, find the relevant page in the new docs system and use the edit options to submit your changes

Option 2:

• Open an issue in elastic/docs-content

💡 Need help?

1. For Elasticians: Ask in #docs Slack channel
2. For external contributors: Open an issue in elastic/docs-content

[leemthompo]

@toby-sutor any reason why this wasn't pursued? :)

[elasticsearchmachine]

Pinging @elastic/core-docs (Team:Docs)

[shainaraskas]

Opened an issue to re-implement this in markdown https://github.com/elastic/docs-content/issues/3287