config: describe 'pathname' value type

We have a dedicated section for various value-types used in the
configuration variables already, because we needed to describe how
booleans and scaled integers can be spelled, and the pathname type
would fit there.

Adjust the description of `include.path`, `core.excludesFile` and
`commit.template` variables slightly to clarify that these variables
are of this type.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -81,13 +81,16 @@ Includes
 
 You can include one config file from another by setting the special
 `include.path` variable to the name of the file to be included. The
+variable takes a pathname as its value, and is subject to tilde
+expansion.
+
+The
 included file is expanded immediately, as if its contents had been
 found at the location of the include directive. If the value of the
 `include.path` variable is a relative path, the path is considered to be
 relative to the configuration file in which the include directive was
-found. The value of `include.path` is subject to tilde expansion: `~/`
-is expanded to the value of `$HOME`, and `~user/` to the specified
-user's home directory. See below for examples.
+found.  See below for examples.
+
 
 Example
 ~~~~~~~
@@ -169,6 +172,13 @@ thing on the same output line (e.g. opening parenthesis before the
 list of branch names in `log --decorate` output) is set to be
 painted with `bold` or some other attribute.
 
+pathname::
+	A variable that takes a pathname value can be given a
+	string that begins with "`~/`" or "`~user/`", and the usual
+	tilde expansion happens to such a string: `~/`
+	is expanded to the value of `$HOME`, and `~user/` to the
+	specified user's home directory.
+
 
 Variables
 ~~~~~~~~~
@@ -584,11 +594,10 @@ be delta compressed, but larger binary media files won't be.
 Common unit suffixes of 'k', 'm', or 'g' are supported.
 
 core.excludesFile::
-	In addition to '.gitignore' (per-directory) and
-	'.git/info/exclude', Git looks into this file for patterns
-	of files which are not meant to be tracked.  "`~/`" is expanded
-	to the value of `$HOME` and "`~user/`" to the specified user's
-	home directory. Its default value is $XDG_CONFIG_HOME/git/ignore.
+	Specifies the pathname to the file that contains patterns to
+	describe paths that are not meant to be tracked, in addition
+	to '.gitignore' (per-directory) and '.git/info/exclude'.
+	Defaults to $XDG_CONFIG_HOME/git/ignore.
 	If $XDG_CONFIG_HOME is either not set or empty, $HOME/.config/git/ignore
 	is used instead. See linkgit:gitignore[5].
 
@@ -1095,9 +1104,8 @@ commit.status::
 	message.  Defaults to true.
 
 commit.template::
-	Specify a file to use as the template for new commit messages.
-	"`~/`" is expanded to the value of `$HOME` and "`~user/`" to the
-	specified user's home directory.
+	Specify the pathname of a file to use as the template for
+	new commit messages.
 
 credential.helper::
 	Specify an external helper to be called when a username or