update docs to use opconfig

Author: FxKu

docs/developer.md

@@ -81,7 +81,7 @@ configuration and RBAC manifests first, e.g.:
 
 ```bash
 kubectl create -f manifests/operatorconfiguration.crd.yaml
-kubectl create -f manifests/postgresql-operator-default-configuration
+kubectl create -f manifests/postgresql-operator-default-configuration.yaml
 kubectl create -f manifests/operator-service-account-rbac.yaml
 sed -e "s/\(image\:.*\:\).*$/\1$TAG/" manifests/postgres-operator.yaml | kubectl create  -f -
 

docs/quickstart.md

@@ -49,8 +49,8 @@ git clone https://github.com/zalando/postgres-operator.git
 cd postgres-operator
 
 # apply the manifests in the following order
-kubectl create -f manifests/operatorconfiguration.crd.yaml  # configuration CRD
-kubectl create -f manifests/postgresql-operator-default-configuration  # default configuration
+kubectl create -f manifests/operatorconfiguration.crd.yaml  # CRD definition
+kubectl create -f manifests/postgresql-operator-default-configuration.yaml  # default configuration
 kubectl create -f manifests/operator-service-account-rbac.yaml  # identity and permissions
 kubectl create -f manifests/postgres-operator.yaml  # deployment
 ```