feat(cli): Implement address flag for boundary targets create/update

This commit adds CLI support for addresses to be attached directly to a
Target, for all current types of Target (ssh and tcp).

It also clarifies the relevant documentation regarding the autogen of
API option functionality.

api/targets/target.gen.go

@@ -37,6 +37,7 @@ type Target struct {
 	InjectedApplicationCredentialSources   []*CredentialSource    `json:"injected_application_credential_sources,omitempty"`
 	Attributes                             map[string]interface{} `json:"attributes,omitempty"`
 	AuthorizedActions                      []string               `json:"authorized_actions,omitempty"`
+	Address                                string                 `json:"address,omitempty"`
 
 	response *api.Response
 }