title: WordPress: add check-boxes to custom taxonomy add/edit form
body: <p>I need to add a list of check-boxes to custom taxonomy add/edit form.
  I have this code for adding a text field for custom taxonomy form in my plugin and it works fine:</p>
  
  <pre><code>    &lt;?php
      function taxonomy_edit_meta_field($term) {
          $t_id = $term-&gt;term_id;
          $term_meta = get_option( "taxonomy_$t_id" ); 
      ?&gt;
  
          &lt;tr class="form-field"&gt;
              &lt;th scope="row" valign="top"&gt;&lt;label for="term_meta[custom_term_meta]"&gt;&lt;?php _e( 'Term:' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
              &lt;td&gt;
                  &lt;input type="text" name="term_meta[custom_term_meta]" id="term_meta[custom_term_meta]" value="&lt;?php echo esc_attr( $term_meta['custom_term_meta'] ) ? esc_attr( $term_meta['custom_term_meta'] ) : ''; ?&gt;"&gt;
              &lt;/td&gt;
          &lt;/tr&gt;
  
      &lt;?php
      }
      add_action( 'product_cat_edit_form_fields', 'taxonomy_edit_meta_field', 10, 2 );
  
      function save_taxonomy_custom_meta( $term_id ) {
          if ( isset( $_POST['term_meta'] ) ) {
              $t_id = $term_id;
              $term_meta = get_option( "taxonomy_$t_id" );
              $cat_keys = array_keys( $_POST['term_meta'] );
              foreach ( $cat_keys as $key ) {
                  if ( isset ( $_POST['term_meta'][$key] ) ) {
                      $term_meta[$key] = $_POST['term_meta'][$key];
                  }
              }
              update_option( "taxonomy_$t_id", $term_meta );
          }
      }  
      add_action( 'edited_product_cat', 'save_taxonomy_custom_meta', 10, 2 );  
      add_action( 'create_product_cat', 'save_taxonomy_custom_meta', 10, 2 );
  </code></pre>
  
  <p>How I can add a list of check-boxes in the same way?</p>