created ide session unknown error page following slack message (#5960)

## What are you changing in this pull request and why?
<!---
Describe your changes and why you're making them. If related to an open 
issue or a pull request on dbt Core, then link to them here! 

To learn more about the writing conventions used in the dbt Labs docs,
see the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md).
-->

## Checklist
<!--
Uncomment when publishing docs for a prerelease version of dbt:
- [ ] Add versioning components, as described in [Versioning
Docs](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-entire-pages)
- [ ] Add a note to the prerelease version [Migration
Guide](https://github.com/dbt-labs/docs.getdbt.com/tree/current/website/docs/docs/dbt-versions/core-upgrade)
-->
- [ ] 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.
- [ ] 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).
- [ ] Add a checklist item for anything that needs to happen before this
PR is merged, such as "needs technical review" or "change base branch."

Adding or removing pages (delete if not applicable):
- [ ] Add/remove page in `website/sidebars.js`
- [ ] Provide a unique filename for new pages
- [ ] Add an entry for deleted pages in `website/vercel.json`
- [ ] Run link testing locally with `npm run build` to update the links
that point to deleted pages

I have created a PR following a Slack message from CSE representative
regarding "Your IDE session experienced an unknown error and was
terminated. Please contact support" error.

---------

Co-authored-by: Ly Nguyen <107218380+nghi-ly@users.noreply.github.com>

website/docs/faqs/Troubleshooting/ide-session-unknown-error.md

@@ -0,0 +1,19 @@
+---
+title: I'm receiving an 'Your IDE session experienced an unknown error and was terminated. Please contact support'.
+description: "Add a repository when seeing IDE unknown error"
+sidebar_label: 'Receiving unknown error in the IDE'
+
+---
+
+If you're seeing the following error when you launch the dbt Cloud IDE, it could be due to a few scenarios but, commonly, it indicates a missing repository:
+
+```shell
+
+Your IDE session experienced an unknown error and was terminated. Please contact support.
+
+```
+
+You can try to resolve this by adding a repository like a [managed repository](/docs/collaborate/git/managed-repository) or your preferred Git account. To add your Git account, navigate to **Project** > **Repository** and select your repository.
+
+
+If you're still running into this error, please contact the Support team at support@getdbt.com for help.