chore(common): fix broken slug

Author: ntacheva

knowledge-base/pdfviewer-upload-controls-visibility.md

@@ -32,7 +32,7 @@ This knowledge base article also answers the following questions:
 
 ## Solution
 
-To control the visibility of Upload component and its dropzone in the `TelerikPdfViewer` while a PDF is loading, apply custom CSS to hide the upload controls. To achieve that, use the [`OnOpen`](slug://components/pdfviewer/events#onopen) event to apply a CSS class with the required styles that hide the controls until the PDF file is loaded successfully.
+To control the visibility of Upload component and its dropzone in the `TelerikPdfViewer` while a PDF is loading, apply custom CSS to hide the upload controls. To achieve that, use the [`OnOpen`](slug://pdfviewer-events#onopen) event to apply a CSS class with the required styles that hide the controls until the PDF file is loaded successfully.
 
 ````RAZOR
 <TelerikPdfViewer Data="@PdfSource"