Fix the structured-metadata docs page (grafana#11518)

**What this PR does / why we need it**:
This little typo may confuse somebody if they would copy/paste the
example.

**Checklist**
- [x] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [ ] Documentation added
- [ ] Tests updated
- [ ] `CHANGELOG.md` updated
- [ ] If the change is worth mentioning in the release notes, add
`add-to-release-notes` label
- [ ] Changes that require user attention or interaction to upgrade are
documented in `docs/sources/setup/upgrade/_index.md`
- [ ] For Helm chart changes bump the Helm chart version in
`production/helm/loki/Chart.yaml` and update
`production/helm/loki/CHANGELOG.md` and
`production/helm/loki/README.md`. [Example
PR](grafana@d10549e)
- [ ] If the change is deprecating or removing a configuration option,
update the `deprecated-config.yaml` and `deleted-config.yaml` files
respectively in the `tools/deprecated-config-checker` directory.
[Example
PR](grafana@0d4416a)

Co-authored-by: Michel Hollands <[email protected]>

docs/sources/get-started/labels/structured-metadata.md

@@ -42,7 +42,7 @@ You can use labels of structured metadata to filter log line using a [label filt
 For example, if you have a label `trace_id` attached to some of your log lines as structured metadata, you can filter log lines using:
 
 ```logql
-{job="example"} | trace_id="0242ac120002"`
+{job="example"} | trace_id="0242ac120002"
 ```
 
 Of course, you can filter by multiple labels of structured metadata at the same time: