Button directive does not support Markdown link references

[theletterf]

Describe the bug

When using the button directive with a Markdown link reference, such as:

:::{button}
[Open][kibana-url]
:::

kibana-url: <https://foo.example.com>

docs-builder throws the following error:

Button directive must contain only a single Markdown link. Use: :::{button}
[text](url)
:::

It appears that only raw links in the form [text](url) are supported, and link reference syntax [text][id] is not processed. This is valid Markdown and should be supported.

Expected behavior

The button directive should accept both raw Markdown links and Markdown link references. The example above should render a functional button just like a direct link.

Steps to reproduce

Steps to reproduce:

1. Use the following snippet in a doc file:

   :::{button}
   [Open][kibana-url]
   :::
   
   kibana-url: <https://foo.example.com>

2. Build the documentation with docs-builder.
3. Observe the error: Button directive must contain only a single Markdown link.

Tooling

true,false,false

View original Slack conversation

[kuisathaverat]

this use case also fails

:::{button}
[Logs](https://example.kb.us-west2.gcp.elastic-cloud.com/app/discover#/?_g=(filters:!(),refreshInterval:(pause:!t,value:60000),time:(from:now-15h,to:now))&_a=(columns:!(),dataSource:(type:esql),filters:!(),interval:auto,query:(esql:'FROM%20logs*,-logstash*,filebeat-*%20%7C%20WHERE%20service.name%20%3D%3D%20%22apm-oblt%22'),sort:!())&_tab=(tabId:'43c2b949-f679-43a8-bf68-9bf209c2fc5a'))
:::