Deprecate initializer and registry-server

Per a discussion on the olm-dev triage call on Feb 4th, it was agreed that both the `initializer` and `registry-server` binaries should be deprecated in favor of `opm` equivalent commands.

Author: cdjohnson

README.md

@@ -8,8 +8,10 @@ Operator Registry runs in a Kubernetes or OpenShift cluster to provide operator
 This project provides the following binaries:
 
  * `opm`, which generates and updates registry databases as well as the index images that encapsulate them.
- * `initializer`, which takes as an input a directory of operator manifests and outputs a sqlite database containing the same data for querying.
+ * `initializer`, which takes as an input a directory of operator manifests and outputs a sqlite database containing the same data for querying
+   * Deprecated - use `opm registry|index add` instead 
  * `registry-server`, which takes a sqlite database loaded with manifests, and exposes a gRPC interface to it.
+   * Deprecated - use `opm registry serve` instead 
  * `configmap-server`, which takes a kubeconfig and a configmap reference, and parses the configmap into the sqlite database before exposing it via the same interface as `registry-server`.
 
 And libraries: