Fix config example for dbt_project.yml (#4443)

## Previews
- [Semantic
models](https://docs-getdbt-com-git-dbeatty-semantic-model-conf-4886b9-dbt-labs.vercel.app/docs/build/semantic-models)

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

Within `dbt_project.yml`, resource types have dashes (`-`) instead of
underscores (`_`), so we need to update this code example accordingly.

### Backstory

Within the description for
#4180, I added some
examples of what I _guessed_ the syntax would be, but I didn't specify
that these were completely unverified guesses 😬.

This particular example got missed during #4281.

### 🎩

<img width="500" alt="image"
src="https://github.com/dbt-labs/docs.getdbt.com/assets/44704949/b270bc87-eb50-446d-9cf6-db7da5fda2a5">

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
and [About
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
so my content adheres to these guidelines.
- [x] I have verified that the code examples work
- [x] I have checked that the preview renders correctly

---------

Co-authored-by: mirnawong1 <[email protected]>

website/docs/docs/build/semantic-models.md

@@ -123,14 +123,18 @@ semantic_models:
     config:
       enabled: true | false
       group: some_group
+      meta:
+        some_key: some_value
 ```
 
 Semantic model config in `dbt_project.yml`:
 ```yml
-semantic_models:
+semantic-models:
   my_project_name:
     +enabled: true | false
     +group: some_group
+    +meta:
+      some_key: some_value
 ```
 
 </VersionBlock>