patman: additionally honor a local .patman config file

This enables versioning a project specific patman configuration file.
It also makes it possible to declare the project name, which is not a
useful thing to do in $HOME/.patman.  A new test is added, along
updated documentation.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@savoirfairelinux.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/patman.rst b/tools/patman/patman.rst
index 395fc0c..d7994c8 100644
--- a/tools/patman/patman.rst
+++ b/tools/patman/patman.rst
@@ -74,7 +74,7 @@
 During the first run patman creates a config file for you by taking the default
 user name and email address from the global .gitconfig file.
 
-To add your own, create a file ~/.patman like this::
+To add your own, create a file `~/.patman` like this::
 
     # patman alias file
 
@@ -85,6 +85,12 @@
     wolfgang: Wolfgang Denk <wd@denx.de>
     others: Mike Frysinger <vapier@gentoo.org>, Fred Bloggs <f.bloggs@napier.net>
 
+Patman will also look for a `.patman` configuration file at the root
+of the current project git repository, which makes it possible to
+override the `project` settings variable or anything else in a
+project-specific way. The values of this "local" configuration file
+take precedence over those of the "global" one.
+
 Aliases are recursive.
 
 The checkpatch.pl in the U-Boot tools/ subdirectory will be located and