Fix typos in doc and comments

Changes persistant -> persistent. www.dictionary.com does not know
persistant (with an A), but should it be one of those things you can
spell in more than one correct way, let me know.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/Changes b/Documentation/Changes
index abee7f5..73a8617 100644
--- a/Documentation/Changes
+++ b/Documentation/Changes
@@ -201,7 +201,7 @@
 ----
 udev is a userspace application for populating /dev dynamically with
 only entries for devices actually present.  udev replaces the basic
-functionality of devfs, while allowing persistant device naming for
+functionality of devfs, while allowing persistent device naming for
 devices.
 
 FUSE