Add links to message tag spec from batch and account-tag

extensions/account-tag-3.2.md

@@ -7,7 +7,7 @@ copyrights:
     period: "2013-2015"
     email: "grawity@gmail.com"
 ---
-The `account-tag` capability causes the server to add a message-tag containing
+The `account-tag` capability causes the server to add a [message tag][] containing
 the command sender's services account to commands sent to the client that has
 requested this capability. It supersedes the `identify-msg` extension.
 
@@ -46,3 +46,5 @@ This extension supersedes `identify-msg`. This extension does not deprecate
 just the account name. Similarly, this extension does not deprecate
 `account-notify`, as the latter provides real-time notifications while this
 extension does not.
+
+[message tag]: ../extensions/message-tags.html

extensions/batch-3.2.md

@@ -45,7 +45,7 @@ Reference tag MUST contain only ASCII letters, numbers, and/or hyphen, and MUST
 The `type` parameter indicates how messages are associated.
 The meaning of the additional parameters (if any) depend on the type.
 
-The batched events MUST use `batch` message tag referring to the batch's reference tag.
+The batched events MUST use `batch` [message tag][] referring to the batch's reference tag.
 Messages before start and after end of a batch (including start and end messages of that batch) MUST NOT refer to that batch.
 
 For every started batch, server MUST end that batch.
@@ -120,6 +120,7 @@ Notice that PRIVMSG line will be processed when batch `outer` ends,
 because end of batch `inner` is tagged by batch `outer`.
 The order in which these two batches start doesn't matter.
 
+[message tag]: ../extensions/message-tags.html
 
 ## Errata