Add Elasticsearch semantic search quickstart

[lcawl]

This PR aims to port content from https://www.elastic.co/getting-started/enterprise-search/build-a-semantic-search-experience into the https://www.elastic.co/docs/solutions/search/get-started section of the documentation.

Some significant changes include:

• Rather than requiring a crawler to ingest sample documents, it uses the ones provided in the index creation workflow (since we want to defer the complexity of ingestion for early users). If the crawler example needs to be ported to the docs, that can be accomplished in a more advanced workflow.
• Rather than covering both semantic search and hybrid search, it covers only the former. Hybrid search will be covered in a separate page.
• Rather than Query DSL examples, it uses ES|QL in Discover.
• Since the steps apply to both Serverless and Stack contexts with minor variations, those variations are both covered.

NOTE: To align with #1929, the new semantic search page is grouped into a quickstart section. I think after all the getting-started guides are migrated into this section we can revisit how/if the API quickstarts can also be included in this section.

Preview

https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1922/solutions/search/get-started/semantic-search

[github-actions]

🔍 Preview links for changed docs:

• solutions/search/get-started/quickstarts.md
• solutions/search/get-started/semantic-search.md
• solutions/search/serverless-elasticsearch-get-started.md

🔔 The preview site may take up to 3 minutes to finish building. These links will become live once it completes.

[theletterf]

Love the overall structure and the use of the stepper!

[florent-leborgne]

+1 on the stepper

You can hosts gifs on Contentstack as well in case we don't want too heavy files stored in GH

[szabosteve]

This is great, thank you for creating it! I left a couple of comments, mostly nits.

[lcawl]

You can hosts gifs on Contentstack as well in case we don't want too heavy files stored in GH

Thanks @florent-leborgne! I've switched to linking to contentstack in 6afc299

[leemthompo]

I just had a few ideas and observations reading through this :)

[github-actions]

🔍 Preview links for changed docs

• solutions/search/get-started/quickstarts.md
• solutions/search/get-started/semantic-search.md

[leemthompo]

LGTM with a few straggling optionals :)

NOTE: To align with #1929, the new semantic search page is grouped into a quickstart section. I think after all the getting-started guides are migrated into this section we can revisit how/if the API quickstarts can also be included in this section.

My instinct is that we should group them together as soon as possible, feels a little hidden in this new section. They're all hands-on guides, just using different interfaces.