doc: update default port val in readme

Signed-off-by: Alexander Bezzubov <bzz@apache.org>

Author: bzz

README.md

@@ -44,7 +44,7 @@ $ lookout-sdk review -v ipv4://localhost:2001 \
 | -- | -- | -- |
 | `GOMETALINT_HOST` | `0.0.0.0` | IP address to bind the gRCP serve |
 | `GOMETALINT_PORT` | `2001` | Port to bind the gRPC server |
-| `GOMETALINT_SERVER_URL` | `ipv4://localhost:10302` | gRPC URL of the [Data service](https://github.com/src-d/lookout/tree/master/docs#components)
+| `GOMETALINT_DATA_SERVICE_URL` | `ipv4://localhost:10301` | gRPC URL of the [Data service](https://github.com/src-d/lookout/tree/master/docs#components)
 | `GOMETALINT_LOG_LEVEL` | `info` | Logging level ("info", "debug", "warning" or "error") |