Merge ~stefanor/dkimpy-milter:table-docs into dkimpy-milter:master

[Stefano Rivera]

Clarify documentation around SigningTable and KeyTable

I recently had to migrate my dkimpy setup to SigningTable, to use selector names compatible with debian.org's policy.

From my reading of the docs, I assumed I needed to use separate key names for RSA and ed25519 keys, and then select them both in SigningTable. Turned out to be wrong.

[Scott Kitterman (kitterman)]

Looks good. Thanks.

review: Approve

diff --git a/README.md b/README.md
index 9d82735..49efe6f 100644
--- a/README.md
+++ b/README.md
@@ -136,9 +136,9 @@ for the above might look like this:
 	comkey	example.com:bar:/usr/local/etc/dkim/keys/excom
 	netkey	example.net:baz:/usr/local/etc/dkim/keys/exnet
 
-If also signing with ed25519, specify a KeyTableEd25519 pointing to the keys
-needed for ed25519.  Both KeyTable and KeyTableEd25519 are evaluated if there
-is a SigningTable (see below).
+If also signing with ed25519, specify a KeyTableEd25519, with the same
+names, pointing to the keys needed for ed25519.  Both KeyTable and
+KeyTableEd25519 are evaluated if there is a SigningTable (see below).
 
 Per the documentation, multi-field data sets that are made of flat files have
 the fields separated by colons, but the key and value(s) are separated by
diff --git a/man/dkimpy-milter.conf.5.in b/man/dkimpy-milter.conf.5.in
index 9a776af..45e3097 100644
--- a/man/dkimpy-milter.conf.5.in
+++ b/man/dkimpy-milter.conf.5.in
@@ -428,7 +428,7 @@ of this field.
 .TP
 .I SigningTable (dataset)
 
-Defines a table used to select one or more signing identities to apply to a message based on the address found in the From: header field. Keys in this table vary depending on the type of table used; values in this data set should include one field that contains a name found in the KeyTable (see above) that identifies which key should be used in generating the signature, and an optional second field naming the signer of the message that will be included in the "i=" tag in the generated signature. Note that the "i=" value will not be included in the signature if it conflicts with the signing domain (the "d=" value).
+Defines a table used to select a signing identity to apply to a message based on the address found in the From: header field. Keys in this table vary depending on the type of table used; values in this data set should include one field that contains a name found in the KeyTable (see above) that identifies which key should be used in generating the signature, and an optional second field naming the signer of the message that will be included in the "i=" tag in the generated signature. Note that the "i=" value will not be included in the signature if it conflicts with the signing domain (the "d=" value).
 
 If the first field contains only a "%" character, it will be replaced by the domain found in the From: header field. Similarly, within the optional second field, any "%" character will be replaced by the domain found in the From: header field.