docs: explain how to contribute code

README.GIT

@@ -80,5 +80,26 @@ you'll need to run that "make install" command with root privileges.
 Problems?
 ---------
 
-Please submit any bugs in the git repository using the Savannah project's
+Please submit any bugs you find in the code in git via the bug tracker
-bug tracker (https://savannah.gnu.org/bugs/?group=nano).
+on Savannah (https://savannah.gnu.org/bugs/?group=nano).
+
+
+Contributing something
+----------------------
+
+If you have a fix for a bug, or the code for a new or improved feature,
+first create a branch off of master:
+
+    $ git checkout -b somename
+
+Then change the code so it does what you want, and commit it, with in the
+commit message (after the one-line summary) a rationale for the change:
+
+    $ git commit -as
+
+Then create a patch (or patches):
+
+    $ git format-patch master
+
+Send that patch (or patches) to <nano-devel@gnu.org>, as an attachment
+or with git send-email.