meta config for semantic models (#4218)

related to: #4180
related to: #4281

## What are you changing in this pull request and why?
- Mention config in `dbt_project.yml` (like for models, seeds, and
snapshots)
- Match the style for other resource types for
`models/semantic_models.yml`
- Clarify that `meta` is no longer "always" available as a top-level key
(see [#8766](dbt-labs/dbt-core#8766))

## Other

- Here's an open issue to add `meta` config for metrics:
[#3957](#3957)
- Opened an issue to add version blocks for any other resource types for
which it is applicable:
[#4224](#4224)
- Opened an issue to add code examples to [`meta`
](https://docs.getdbt.com/reference/resource-configs/meta) for
`dbt_project.yml` (like
[`enabled`](https://docs.getdbt.com/reference/resource-configs/enabled)
has them):
[#4415](#4415)


## 🎩 

### Previews
-
[1.6](https://docs-getdbt-com-git-dbeatty-semantic-models-met-b30fa1-dbt-labs.vercel.app/reference/resource-configs/meta?version=1.6)
-
[1.7](https://docs-getdbt-com-git-dbeatty-semantic-models-met-b30fa1-dbt-labs.vercel.app/reference/resource-configs/meta?version=1.7)

### v1.7

<img width="500" alt="image"
src="https://github.com/dbt-labs/docs.getdbt.com/assets/44704949/09de14e0-dd5b-40ef-8d9b-f1cd34a602a9">


## Checklist
- [x] I have tested that the code examples work
- [x] I have tested that the changes look correct in the Vercel preview
- [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.

website/docs/reference/resource-configs/meta.md

@@ -184,20 +184,20 @@ Support for grouping semantic models was added in dbt Core v1.7
 
 <VersionBlock firstVersion="1.7"> 
 
-<File name='semantic_models.yml'>
+<File name='models/semantic_models.yml'>
 
 ```yml
 semantic_models:
-  - name: semantic_people
-    model: ref('people')
+  - name: semantic_model_name
     config:
       meta: {<dictionary>}
 
 ```
-The `meta` configuration can be nusted under the `config` key. 
 
 </File>
 
+The `meta` config can also be defined under the `semantic-models` config block in `dbt_project.yml`. See [configs and properties](/reference/configs-and-properties) for details.
+
 </VersionBlock>
 
 </TabItem>
@@ -207,7 +207,7 @@ The `meta` configuration can be nusted under the `config` key.
 ## Definition
 The `meta` field can be used to set metadata for a resource. This metadata is compiled into the `manifest.json` file generated by dbt, and is viewable in the auto-generated documentation.
 
-Depending on the resource you're configuring, `meta` may be available within the `config` property, or as a top-level key. (For backwards compatibility, `meta` is always supported as a top-level key, though without the capabilities of config inheritance.)
+Depending on the resource you're configuring, `meta` may be available within the `config` property, and/or as a top-level key. (For backwards compatibility, `meta` is often (but not always) supported as a top-level key, though without the capabilities of config inheritance.)
 
 
 ## Examples