This works starting v1.6: --select resource_type:source (#6115)

[Preview](https://docs-getdbt-com-git-dbeatty10-patch-3-dbt-labs.vercel.app/reference/node-selection/methods#the-resource_type-method)

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

Prior to dbt v1.6, `--select resource_type:source` wasn't an option, and
this was the alternative:

```bash
dbt list --resource-type source
```

But now that it's available for all supported versions of dbt, we can
update the docs to remove this caveat.

## 🎩 

Before:

<img width="600" alt="image"
src="https://github.com/user-attachments/assets/75537bba-c8a5-4e2d-88b1-7c6e0f715315">

After:

<img width="600" alt="image"
src="https://github.com/user-attachments/assets/161d2f37-c0ea-4d88-899c-b57afb370520">


## Checklist
- [x] I have reviewed 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.

Co-authored-by: Mirna Wong <[email protected]>
Co-authored-by: Matt Shaver <[email protected]>

website/docs/reference/node-selection/methods.md

@@ -44,13 +44,8 @@ Use the `resource_type` method to select nodes of a particular type (`model`, `t
 
   ```bash
 dbt build --select "resource_type:exposure"    # build all resources upstream of exposures
-dbt list --select "resource_type:test"    # list all tests in your project
-```
-
-Note: This method doesn't work for sources, so use the [`--resource-type`](/reference/commands/list) option of the list command instead:
-
-  ```bash
-dbt list --resource-type source
+dbt list --select "resource_type:test"         # list all tests in your project
+dbt list --select "resource_type:source"       # list all sources in your project
 ```
 
 ### The "path" method