add link to Docker quickstart in github README (#10299)
Per suggestion in comment https://github.com/apache/druid/pull/9262#issuecomment-675732237, I think this should eventually result in the copy mirrored on dockerhub to also be updated, if I understand how things work. Only the github `README.md` has been updated, not the `README.template` used for src and bin packages because presumably if you are reading from either of those you are just going to run locally and so the local quickstart is appropriate.
diff --git a/README.md b/README.md
index 8eec353..0bf9156 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@
### Getting started
-You can get started with Druid with our [quickstart](https://druid.apache.org/docs/latest/tutorials/quickstart.html).
+You can get started with Druid with our [local](https://druid.apache.org/docs/latest/tutorials/quickstart.html) or [Docker](http://druid.apache.org/docs/latest/tutorials/docker.html) quickstart.
Druid provides a rich set of APIs (via HTTP and [JDBC](https://druid.apache.org/docs/latest/querying/sql.html#jdbc)) for loading, managing, and querying your data.
You can also interact with Druid via the [built-in console](https://druid.apache.org/docs/latest/operations/druid-console.html) (shown below).
