Enabled verbose logging for dev guide. (#504)

This can help dev to check more detail for what is wrong with
`dep ensure` if there are some errors.

docs/developer-guide.md

@@ -11,7 +11,7 @@
 Pull in the dependencies
 
 ```
-dep ensure --vendor-only
+dep ensure --vendor-only -v
 ```
 
 You can build all images from source.
@@ -25,6 +25,6 @@ You can build all images from source.
 Suggestion API is defined as GRPC service at `pkg/api/v1alpha1/api.proto`. Source code is [here](https://github.com/kubeflow/katib/blob/master/pkg/api/v1alpha1/api.proto). You can attach new algorithm easily.
 
 - implement suggestion API
-- make k8s service named vizier-suggestion-{ algorithm-name } and expose port 6789
+- make k8s service named `vizier-suggestion-{ algorithm-name }` and expose port 6789
 
 And to add new suggestion service, you don't need to stop components ( vizier-core, modeldb, and anything) that are already running.