Fix join_to_timespine indentation (#6686)

## What are you changing in this pull request and why?
Resolves #6685 

## 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: Matt Shaver <60105315+matthewshaver@users.noreply.github.com>

website/docs/docs/build/metrics-overview.md

@@ -271,9 +271,9 @@ metrics:
       measure:
         name: cancellations_usd  # Specify the measure you are creating a proxy for.
         fill_nulls_with: 0
+        join_to_timespine: true
     filter: |
       {{ Dimension('order__value')}} > 100 and {{Dimension('user__acquisition')}} is not null
-    join_to_timespine: true
 ```
 </File>