New server uses read protocol, to eh, read. (#3444)

docs/migration.md

@@ -129,7 +129,7 @@ The data format in Prometheus 2.0 has completely changed and is not backwards
 compatible with 1.8. To retain access to your historic monitoring data we
 recommend you run a non-scraping Prometheus instance running at least version
 1.8.1 in parallel with your Prometheus 2.0 instance, and have the new server
-read existing data from the old one via the remote write protocol.
+read existing data from the old one via the remote read protocol.
 Your Prometheus 1.8 instance should be started with the following flags and an
 config file containing only the `external_labels` setting (if any):