[mdx → asciidoc] Add AsciiDoc serverless files (#168)

* migrate mdx to asciidoc

* hard code stack version

* try including shared attributes using asciidoc-dir

* clean up landing page, add project-settings, add badges, replace doc related articles

* fix broken link

* clean up links

* fix attributes in parentheses

* add missing attributes

* fix cloud regions page

* fix connections page, add missing security pages

* qa general

* qa elasticsearch

* qa devtools

* qa project-settings

* qa hidden pages

* simplify landing page

* Fix MDX syntax, broken links, and use of updated variables (#159)

* fix mdx syntax and links

* fix duplicate Elastic

* clean post rebase and qa

* restructure index

* update readme

* flatten into one pages directory again

* move non-published files back to pages directory

* use asciidoc-dir

* update id to fix redirect

* comment out description and keywords

Author: colleenmcginnis

README.md

@@ -1,14 +1,14 @@
 # docs-content
 
-This repo contains most of our Elastic Serverless documentation, including: 
+This repo contains most of our Elastic Serverless documentation, including:
 
 - [Overview content](https://www.elastic.co/docs/current/serverless)
 - [Elasticsearch](https://www.elastic.co/docs/current/serverless/elasticsearch/what-is-elasticsearch-serverless)
 - [Dev tools](https://www.elastic.co/docs/current/serverless/devtools/developer-tools)
 - [Project and management settings](https://www.elastic.co/docs/current/serverless/project-and-management-settings)
 
 > Not the docs you're looking for? Try the following:
-> 
+>
 > - For Elastic Observability, visit [elastic/observability-docs](https://github.com/elastic/observability-docs).
 > - For Elastic Security, visit [elastic/security-docs](https://github.com/elastic/security-docs).
 > - For all other documentation, click the **✏️ edit** button on any page to jump to its source in GitHub.
@@ -21,7 +21,7 @@ All documentation pull requests automatically add the [@platform-docs](https://g
 
 If you find any bugs in our documentation, or want to request an enhancement, then you can open an issue using our template. We also welcome contributions in the form of PRs. Before you submit a PR, make sure that you have signed our [Contributor License Agreement](https://www.elastic.co/contributor-agreement/).
 
-This documentation uses a custom syntax written in [MDX](https://mdxjs.com/). In many cases, you only need to know plain markdown to contribute. We'll add a public component reference and additional contribution guidelines in future. Elasticians can refer to our [internal syntax reference](https://docs.elastic.dev/docsmobile/syntax).
+This documentation uses [AsciiDoc](https://github.com/elastic/docs?tab=readme-ov-file#asciidoc-guide).
 
 ## Preview the docs