docs: fix title-property JSDoc [skip ci] (#419)

based on https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/title

fix #293

src/vaadin-text-field.html

@@ -130,7 +130,7 @@
             },
 
             /**
-             * Message to show to the user when validation fails.
+             * The text usually displayed in a tooltip popup when the mouse is over the field.
              */
             title: {
               type: String