fix typo

specification/modules/end_to_end_encryption.rst

@@ -159,7 +159,7 @@ It is therefore expected that each client will maintain a list of devices for a
 number of users (in practice, typically each user with whom we share an
 encrypted room). Furthermore, it is likely that this list will need to be
 persisted between invocations of the client application (to preserve device
-verification data and to alert Alice if Bob suddently gets a new
+verification data and to alert Alice if Bob suddenly gets a new
 device).
 
 Alice's client can maintain a list of Bob's devices via the following