Add default revalidate value to docs (#25238)

This makes sure to mention the default revalidate value is `false` or to not revalidate since it previously only mentions it's optional. 

## Documentation / Examples

- [x] Make sure the linting passes

docs/basic-features/data-fetching.md

@@ -73,7 +73,7 @@ The `context` parameter is an object containing the following keys:
 `getStaticProps` should return an object with:
 
 - `props` - An **optional** object with the props that will be received by the page component. It should be a [serializable object](https://en.wikipedia.org/wiki/Serialization)
-- `revalidate` - An **optional** amount in seconds after which a page re-generation can occur. More on [Incremental Static Regeneration](#incremental-static-regeneration)
+- `revalidate` - An **optional** amount in seconds after which a page re-generation can occur (defaults to: `false` or no revalidating). More on [Incremental Static Regeneration](#incremental-static-regeneration)
 - `notFound` - An **optional** boolean value to allow the page to return a 404 status and page. Below is an example of how it works:
 
   ```js