[DOCS-12837] Add monitor title/description guidelines

[evazorro]

What does this PR do? What is the motivation?

Adds back guidelines for technology partners on creating monitor templates (wording guidance for the title and description; removed in #32291). It's useful content for partners, plus the Docs team refers to these guidelines when reviewing integration submissions.

Merge instructions

Merge readiness:

• Ready for merge

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/eva/DOCS-12837-monitor-guidelines/extend/integrations/create-an-integration-monitor-template

[rtrieu]

hi eva, left some suggestions to tighten things up a bit and for consistency with the UI. here to chat through any of this!

[evazorro]

@dd-dominic adding you as a reviewer in case you have time this week to look at one last docs change 🥹

[dd-dominic]

A condensed version of this exists in Step 4 of "Add your monitor to your integration" - so we should remove or replace that with this new content.

[dd-dominic]

Suggested change

	- Use the active voice and start with the resource or metric, followed by a verb.
	- Use active voice and start with the resource or metric, followed by a verb.

[evazorro]

A condensed version of this exists in Step 4 of "Add your monitor to your integration" - so we should remove or replace that with this new content.

@dd-dominic Argh, good call. I tried out adding the tables inline within that step: what are your thoughts? If it makes the section too long, maybe I give up on adding them back to the doc and just put them in internal review docs somewhere.

[dd-dominic]

@evazorro I think that looks fine! It's a shorter page than our other docs, so not too much going on.