CHANGELOG.md: add CSV feature
### Added
- By default the controller-runtime metrics are exposed on port 8383. This is done as part of the scaffold in the main.go file, the port can be adjusted by modifying the `metricsPort` variable. [#786](https://github.com/operator-framework/operator-sdk/pull/786)
+- A new command [`operator-sdk olm-catalog`](https://github.com/operator-framework/operator-sdk/blob/master/doc/sdk-cli-reference.md#olm-catalog) to be used as a parent for SDK subcommands generating code related to Operator Lifecycle Manager (OLM) Catalog integration, and subcommand [`operator-sdk olm-catalog gen-csv`](https://github.com/operator-framework/operator-sdk/blob/master/doc/sdk-cli-reference.md#gen-csv) which generates a Cluster Service Version for an operator so the OLM can deploy the operator in a cluster. ([#673](https://github.com/operator-framework/operator-sdk/pull/673))
### Changed
