Updating Metrics for 1.3 Changes

[callum-mcdata]

Description & motivation

There are changes to the metric spec coming down the line in v1.3. PR here: dbt-labs/dbt-core#5775

This updates the metric page for the new spec.

To-do before merge

Have docs team review the language

Prerelease docs

If this change is related to functionality in a prerelease version of dbt (delete if not applicable):

• I've added versioning components, as described in "Versioning Docs"
• I've added a note to the prerelease version's Migration Guide

[netlify]

✅ Deploy Preview for docs-getdbt-com ready!

Name	Link
🔨 Latest commit	0de0757
🔍 Latest deploy log	https://app.netlify.com/sites/docs-getdbt-com/deploys/6335b9ce168ed20008e9f5b0
😎 Deploy Preview	https://deploy-preview-1954--docs-getdbt-com.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[callum-mcdata]

@mirnawong1 I've made updates to have querying information present in the metrics page, as well as some other formatting. Should be good for review!

[mirnawong1]

hey @callum-mcdata this looks really great and added some comments and small tweaks for typos etc. other than those changes, looks good to me!

[mirnawong1]

hey @callum-mcdata one thing i noticed, we have an h2 ## Declaring a metric - should this change to ## Defining a metric instead for consistency?