minor text fixes

ChangeLog

@@ -3,7 +3,7 @@ Version 4.4.5.2 'Ardee West':
 	- dual allocation adjusted according to the new TURN-bis draft;
 	- options sha256, sha384, sha512 retired as non-standard;
 	- third-party authorization (oAuth) updated according to the
-	version 14 of the draft;
+	version 16 of the draft;
 	- C++ compilation fixes;
 	- cosmetic fixes;
 	- fixed binary package for CentOS 7.1;

INSTALL

@@ -751,7 +751,7 @@ The oauth_key table fields meanings are:
 
 	kid: the kid of the key;
 
-	ikm_key - (optional) base64-encoded key ("input keying material");
+	ikm_key - base64-encoded key ("input keying material");
 		
 	timestamp - (optional) the timestamp (in seconds) when the key 
 		lifetime starts;