[PATCH v2 3/4] docs/git-credential-store: document XDG file and precedence

[Paul Tan <pyokagan@gmail.com>]

git-credential-store now supports an additional default credential file
at $XDG_CONFIG_HOME/git/credentials. However, ~/.git-credentials takes
precedence over it for backwards compatibility. To make the precedence
ordering explicit, add a new section FILES that lists out the credential
file paths in their order of precedence, and explains how the ordering
affects the lookup, storage and erase operations.

Also update documentation for --store to briefly explain the operations
on multiple files if the --store option is not provided.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
---
 Documentation/git-credential-store.txt | 37 ++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-credential-store.txt b/Documentation/git-credential-store.txt
index bc97071..451c4fa 100644
--- a/Documentation/git-credential-store.txt
+++ b/Documentation/git-credential-store.txt
@@ -31,10 +31,43 @@ OPTIONS
 
 --file=<path>::
 
-	Use `<path>` to store credentials. The file will have its
+	Use `<path>` to lookup and store credentials. The file will have its
 	filesystem permissions set to prevent other users on the system
 	from reading it, but will not be encrypted or otherwise
-	protected. Defaults to `~/.git-credentials`.
+	protected. If not specified, credentials will be searched for from
+	`~/.git-credentials` and `$XDG_CONFIG_HOME/git/credentials`, and
+	credentials will be written to `~/.git-credentials` if it exists, or
+	`$XDG_CONFIG_HOME/git/credentials` if it exists and the former does
+	not. See also <<FILES>>.
+
+[[FILES]]
+FILES
+-----
+
+If not set explicitly with '--file', there are two files where
+git-credential-store will search for credentials in order of precedence:
+
+~/.git-credentials::
+	User-specific credentials file.
+
+$XDG_CONFIG_HOME/git/credentials::
+	Second user-specific credentials file. If '$XDG_CONFIG_HOME' is not set
+	or empty, `$HOME/.config/git/credentials` will be used. Any credentials
+	stored in this file will not be used if `~/.git-credentials` has a
+	matching credential as well. It is a good idea not to create this file
+	if you sometimes use older versions of Git, as support for this file
+	was added fairly recently.
+
+
+For credential lookups, the files are read in the order given above, with the
+first matching credential found taking precedence over credentials found in
+files further down the list.
+
+Credential storage will per default write to the first existing file in the
+list. If none of these files exist, `~/.git-credentials` will be created and
+written to.
+
+When erasing credentials, matching credentials will be erased from all files.
 
 EXAMPLES
 --------
-- 
2.1.4