Add examples for config add and config update in main docblock

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

src/Config_Command.php

@@ -34,6 +34,14 @@
  *     $ wp config get table_prefix
  *     wp_
  *
+ *     # Add a new constant to the wp-config.php file.
+ *     $ wp config add WP_DEBUG true --raw
+ *     Success: Added the constant 'WP_DEBUG' to the 'wp-config.php' file with the raw value 'true'.
+ *
+ *     # Update or add a constant to the wp-config.php file.
+ *     $ wp config update WP_DEBUG false --raw
+ *     Success: Updated the constant 'WP_DEBUG' in the 'wp-config.php' file with the raw value 'false'.
+ *
  *     # Set the WP_DEBUG constant to true.
  *     $ wp config set WP_DEBUG true --raw
  *     Success: Updated the constant 'WP_DEBUG' in the 'wp-config.php' file with the raw value 'true'.