Docs: Fixed docker_sd_configs top level key name (#11803)

**What this PR does / why we need it**:
Misspelling in top level key name, promtail accept docker_sd_config**s**
but not docker_sd_config

**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](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](0d4416a)

Co-authored-by: J Stickler <[email protected]>

docs/sources/send-data/promtail/configuration.md

@@ -1940,7 +1940,7 @@ users with thousands of services it can be more efficient to use the Consul API
 directly which has basic support for filtering nodes (currently by node
 metadata and a single tag).
 
-### docker_sd_config
+### docker_sd_configs
 
 Docker service discovery allows retrieving targets from a Docker daemon.
 It will only watch containers of the Docker daemon referenced with the host parameter. Docker