docs: remove unused editor doc

Author: ghiscoding

frameworks/slickgrid-vue/docs/TOC.md

@@ -16,8 +16,7 @@
 * [Cell Menu (Action Menu)](column-functionalities/cell-menu.md)
 * [Editors](column-functionalities/editors.md)
   * [Autocomplete](column-functionalities/editors/autocomplete-editor.md)
-  * [old Date Picker (flatpickr)](column-functionalities/editors/date-editor-flatpickr.md)
-  * [new Date Picker (vanilla-calendar)](column-functionalities/editors/date-editor-vanilla-calendar.md)
+  * [Date Picker (vanilla-calendar)](column-functionalities/editors/date-editor-vanilla-calendar.md)
   * [LongText (textarea)](column-functionalities/editors/longtext-editor-textarea.md)
   * [Select Dropdown Editor (single/multiple)](column-functionalities/editors/select-dropdown-editor.md)
 * [Filters](column-functionalities/filters/filter-intro.md)