doc: add verbose flag (#154)

README.md

@@ -98,10 +98,11 @@ Kor provides various subcommands to identify and list unused resources. The avai
       --newer-than string           The maximum age of the resources to be considered unused. This flag cannot be used together with older-than flag. Example: --newer-than=1h2m
       --no-interactive              Do not prompt for confirmation when deleting resources. Be careful using this flag!
       --older-than string           The minimum age of the resources to be considered unused. This flag cannot be used together with newer-than flag. Example: --older-than=1h2m
-      --output string               Output format (table, json or yaml) (default "table")
+  -o, --output string               Output format (table, json or yaml) (default "table")
       --slack-auth-token string     Slack auth token to send notifications to. --slack-auth-token requires --slack-channel to be set.
       --slack-channel string        Slack channel to send notifications to. --slack-channel requires --slack-auth-token to be set.
       --slack-webhook-url string    Slack webhook URL to send notifications to
+  -v, --verbose                     Verbose output (print empty namespaces)
 
 ```