docs/guides/firmware-update.md: fix troubleshooting link

Signed-off-by: Michał Kopeć <michal.kopec@3mdeb.com>

Author: mkopec

docs/guides/firmware-update.md

@@ -45,7 +45,7 @@ Then, reboot your machine to apply the update.
     Powering off instead of rebooting as instructed by fwupd will result in
     aborting the update.
 
-If you see any errors during the update, check the [Troubleshooting](../../guides/capsule-update.md#troubleshooting)
+If you see any errors during the update, check the [Troubleshooting](../guides/capsule-update.md#troubleshooting)
 section of the Capsule Update guide.
 
 ## Firmware Update Mode