Document workaround to #17794

wiki/src/news/version_4.8.mdwn

@@ -90,9 +90,18 @@ For more details, read our [[!tails_gitweb debian/changelog desc="changelog"]].
   type <span class="code">'née entrepôt über señor'</span>.
   ([[!tails_ticket 17792]])
 
-* The keyboard layout is not updated automatically when setting the
-  language. For example, setting the language to French doesn't change
-  the keyboard layout to French (AZERTY). ([[!tails_ticket 17794]])
+* The keyboard layout is not applied to the Welcome Screen when
+  automatically selected after you changed the language. ([[!tails_ticket 17794]])
+
+  For example, setting the language to French seems to change the
+  keyboard layout to French (AZERTY) but this change is not applied to
+  the Welcome Screen. This can prevent you from typing the passphrase
+  of your Persistent Storage.
+
+  To change the keyboard layout of the Welcome Screen, select your
+  keyboard layout manually from the **Keyboard Layout** drop-down menu.
+  Do so even if they keyboard layout is automatically selected after you
+  changed the language.
 
 * Tails fails to start with the <span class="code">toram</span> boot
   option. ([[!tails_ticket 17800]])