Support --field=<field> when using wp post term list

Author: danielbachhuber

features/post-term.feature

@@ -50,6 +50,12 @@ Feature: Manage post term
       1
       """
 
+    When I run `wp post term list 1 category --field=slug`
+    Then STDOUT should be:
+      """
+      new
+      """
+
     When I run `wp post term remove 1 category new`
     Then STDOUT should be:
       """

src/WP_CLI/CommandWithTerms.php

@@ -41,6 +41,9 @@ abstract class CommandWithTerms extends \WP_CLI_Command {
 	 * <taxonomy>...
 	 * : One or more taxonomies to list.
 	 *
+	 * [--field=<field>]
+	 * : Prints the value of a single field for each term.
+	 *
 	 * [--fields=<fields>]
 	 * : Limit the output to specific row fields.
 	 *