Add date in YAML front matter (#4547)

## What are you changing in this pull request and why?

Fix copy/pasta error. Add the `date` YAML key in the front matter; this
posts to the community slack channel

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
so my content adheres to these guidelines.
- [x] For [docs
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#about-versioning),
review how to [version a whole
page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
and [version a block of
content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content).

website/docs/docs/dbt-versions/release-notes/02-Nov-2023/explorer-updates-rn.md

@@ -4,6 +4,7 @@ description: "November 2023: New features and UI changes to dbt Explorer, includ
 sidebar_label: "Enhancement: New features and UI changes to dbt Explorer"
 sidebar_position: 08
 tags: [Nov-2023]
+date: 2023-11-28
 ---
 
 dbt Labs is excited to announce the latest features and UI updates to dbt Explorer!

website/docs/docs/dbt-versions/release-notes/02-Nov-2023/job-notifications-rn.md

@@ -4,6 +4,7 @@ description: "November 2023: New quality-of-life improvements for setting up and
 sidebar_label: "Enhancement: Job notifications"
 sidebar_position: 10
 tags: [Nov-2023]
+date: 2023-11-28
 ---
 
 There are new quality-of-life improvements in dbt Cloud for email and Slack notifications about your jobs: 

website/docs/docs/dbt-versions/release-notes/02-Nov-2023/microsoft-fabric-support-rn.md

@@ -4,6 +4,7 @@ description: "November 2023: Public Preview now available for Microsoft Fabric i
 sidebar_label: "New: Public Preview of Microsoft Fabric support"
 sidebar_position: 09
 tags: [Nov-2023]
+date: 2023-11-28
 ---
 
 Public Preview is now available in dbt Cloud for Microsoft Fabric!