DOC-3154: Remove references to skin tool from the tinymce/7 documentation content.

Author: kemister85

modules/ROOT/pages/customize-ui.adoc

@@ -35,7 +35,7 @@ tinymce.init({
 });
 ----
 
-To create a skin interactively, visit http://skin.tiny.cloud/t5/[the {productname} 6 Skin Tool]. For information on manually creating skins for {productname}, see xref:creating-a-skin.adoc[Creating a skin].
+For information on manually creating skins for {productname}, see xref:creating-a-skin.adoc[Creating a skin].
 
 NOTE: Developers often confuse the difference between {productname} "themes" and "skins". A *Skin* in {productname} is used to make changes to the appearance of the editor, for example, colors, margins, padding, fonts, icons, etc. A *Theme* creates the editor construction (left, top, bottom, or right of the editing area - vertical or horizontal, inline or outside, etc.). A skin usually changes the color scheme of a button, dialog, etc. while the theme applies to the whole editor including its functionality and has child skins to change the appearance.