usr/Kconfig: fix typo

Signed-off-by: Alexander E. Patrakov
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

usr/Kconfig

@@ -17,7 +17,7 @@ config INITRAMFS_SOURCE
 	  When multiple directories and files are specified then the
 	  initramfs image will be the aggregate of all of them.
 
-	  See <file:Documentation/early-userspace/README for more details.
+	  See <file:Documentation/early-userspace/README> for more details.
 
 	  If you are not sure, leave it blank.