fix(doc): render index.md's admonition link

[hainenber]

PR Description

Which issue(s) this PR fixes

Fixes issue shown in following screenshot. Captured in https://grafana.com/docs/agent/latest/

Notes to the Reviewer

PR Checklist

[clayton-cornell]

@jdbaldry Can you take a quick look at this. I should have done a make doc build test before I merged the last PR that was raised to fix this link. The <AGENT VERSION> part isn't rendering within the admonition. I'm not sure how to fix this one properly.

Previous PRs

• Fix a cross reference link in a note in the Agent root topic #5464
• Fix a cross reference link in a note in the Agent root topic (v0.37) #5465

This also look broken in v0.36 (wasn't fixed in v0.36 in the previous PRs)

[jdbaldry]

Agh, sorry for this.

I discovered that the Markdown parser does not appreciate whitespace in link definitions. If possible, the best fix is to replace AGENT VERSION with something like AGENT_VERSION everywhere.

[clayton-cornell]

Refer to:

• Add a missing underscore in a link URL in a note admonition #5494
• Fix broken link in Note #5495

[clayton-cornell]

@hainenber I'm going to apply the suggestions and push this fix through. I don't wan tit to lag behind too much and I need the topic fixed for other incoming updates :-) Thanks for spotting this. It's lead to fixing a similar problem in a few other places.

[clayton-cornell]

Approving. The same fix has been applied already to v0.37 and v0.36 docs.