Update old link for pipeline stages. (#2172)

Fixes #2165

cmd/docker-driver/README.md

@@ -174,7 +174,7 @@ To specify additional logging driver options, you can use the --log-opt NAME=VAL
 | `loki-max-backoff`              |    No     |           `10s`            | The maximum amount of time to wait before retrying a batch. Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".                                                                                                                                                   |
 | `loki-retries`                  |    No     |            `10`            | The maximum amount of retries for a log batch.                                                                                                                                                                                                                                |
 | `loki-pipeline-stage-file`      |    No     |                            | The location of a pipeline stage configuration file ([example](./pipeline-example.yaml)). Pipeline stages allows to parse log lines to extract more labels. [see documentation](../../docs/logentry/processing-log-lines.md)                                                  |
-| `loki-pipeline-stages`          |    No     |                            | The pipeline stage configuration provided as a string [see](#pipeline-stages) and  [see documentation](../../docs/logentry/processing-log-lines.md)                                                                                                                           |
+| `loki-pipeline-stages`          |    No     |                            | The pipeline stage configuration provided as a string [see](#pipeline-stages) and  [see documentation](../../docs/clients/promtail/pipelines.md)                                                                                                                           |
 | `loki-tenant-id`                |    No     |                            | Set the tenant id (http header`X-Scope-OrgID`) when sending logs to Loki. It can be overrides by a pipeline stage.                                                                                                                                                            |
 | `loki-tls-ca-file`              |    No     |                            | Set the path to a custom certificate authority.                                                                                                                                                                                                                               |
 | `loki-tls-cert-file`            |    No     |                            | Set the path to a client certificate file.                                                                                                                                                                                                                                    |