[docs] Grammar in Modal documentation (#495)

Fixed an inconsistency. The word "data" was used in both singular and
plural forms. Left the singular form.

Signed-off-by: faisne <96305700+faisne@users.noreply.github.com>

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Signed-off-by: faisne <96305700+faisne@users.noreply.github.com>

website/docs/components/modal/modal.md

@@ -16,7 +16,7 @@ tabName: Design
 
 ### Use the modal window
 
-- To demonstrate secondary data that is not always required (especially if there are a lot of them). Their absence simplifies the interface. Moreover, they don't apply to other pages/reports. _For example, settings, small forms to fill out, step-by-step actions, detailed information about any data._
+- To demonstrate secondary data that is not always required (especially if there is a lot of it). Its absence simplifies the interface. Moreover, it doesn't apply to other pages/reports. _For example, settings, small forms to fill out, step-by-step actions, detailed information about any data._
 - To draw attention to a specific task. _For example, confirming an operation, adding data._
 - To focus on critical information that requires the user's attention. _For example, local news, limiting, deleting an element, or losing information._
 - To view enlarged images or videos.