Update manual of opendkim.conf and RELEASE_NOTE for KeyTable extension

Author: futatuki

RELEASE_NOTES

@@ -13,6 +13,8 @@ release, and a summary of the changes in that release.
 	Make odkim.internal_ip() available to all Lua hooks.  Problem noted
 		by Iosif Fettich.
 	Make bind code DNSSEC-aware.  Patch from Jack Bates.
+	Extend KeyTable to specify signing algorithm.
+		Patch from Yasuhito Futatsuki.
 	Fix dkimf_db_nextpunct() so it doesn't incorrectly identify an encoded
 		hex digit as a value delimiter.
 	Fix issue #8: The password file critical section isn't big enough.

opendkim/opendkim.conf.5.in

@@ -349,15 +349,22 @@ If present, overrides any
 setting in the configuration file.  The data set named here maps each key
 name to three values: (a) the name of the domain to use in the signature's
 "d=" value; (b) the name of the selector to use in the signature's "s=" value;
-and (c) either a private key or a path to a file containing a private key.
+and (c) either a private key or a path to a file containing a private key;
+(d) (optional) signing algorithm to use with this key.
 If the first value consists solely of a percent sign ("%") character,
 it will be replaced by the apparent domain of the sender when generating
 a signature.
 If the third value starts with a slash ("/") character, or "./" or "../",
 then it is presumed to refer to a file from which the private key should
 be read, otherwise it is itself a PEM-encoded private key or a base64-encoded
 DER private key; a "%" in the third value in this case will be replaced by
-the apparent domain name of the sender.  The
+the apparent domain name of the sender.  The fourth field should be one
+of supported siginig algorithms (see
+.I SignatureAlgorithm
+below).
+If it is omited, the algorithm specified in
+.I SignatureAlgorithm
+is used for the key.
 .I SigningTable
 (see below) is used to select records from this table to be used to add
 signatures based on the message sender.