config.txt: move mailmap.* to a separate file

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -367,21 +367,7 @@ include::config/log.txt[]
 
 include::config/mailinfo.txt[]
 
-mailmap.file::
-	The location of an augmenting mailmap file. The default
-	mailmap, located in the root of the repository, is loaded
-	first, then the mailmap file pointed to by this variable.
-	The location of the mailmap file may be in a repository
-	subdirectory, or somewhere outside of the repository itself.
-	See linkgit:git-shortlog[1] and linkgit:git-blame[1].
-
-mailmap.blob::
-	Like `mailmap.file`, but consider the value as a reference to a
-	blob in the repository. If both `mailmap.file` and
-	`mailmap.blob` are given, both are parsed, with entries from
-	`mailmap.file` taking precedence. In a bare repository, this
-	defaults to `HEAD:.mailmap`. In a non-bare repository, it
-	defaults to empty.
+include::config/mailmap.txt[]
 
 man.viewer::
 	Specify the programs that may be used to display help in the

Documentation/config/mailmap.txt

@@ -0,0 +1,15 @@
+mailmap.file::
+	The location of an augmenting mailmap file. The default
+	mailmap, located in the root of the repository, is loaded
+	first, then the mailmap file pointed to by this variable.
+	The location of the mailmap file may be in a repository
+	subdirectory, or somewhere outside of the repository itself.
+	See linkgit:git-shortlog[1] and linkgit:git-blame[1].
+
+mailmap.blob::
+	Like `mailmap.file`, but consider the value as a reference to a
+	blob in the repository. If both `mailmap.file` and
+	`mailmap.blob` are given, both are parsed, with entries from
+	`mailmap.file` taking precedence. In a bare repository, this
+	defaults to `HEAD:.mailmap`. In a non-bare repository, it
+	defaults to empty.