Update README to tell how to checkout a single external package.

1 files changed, 13 insertions, 0 deletions

diff --git a/README b/README
index acc42e4..be8d5b2 100644
--- a/README
+++ b/README
@@ -92,11 +92,24 @@ merge -s subtree" from the upstream branch.
 
 In the `external' case, the copy of the code is not kept here but in the
 `externals/<pkg>' branch in the `elpa' repository.
+
 You can check out all the external packages into the `packages' directory
 with the command:
 
    make externals
 
+You can check out a specific external PACKAGE into the `packages'
+directory with these commands:
+
+   cd packages
+   git clone --reference .. --single-branch --branch externals/PACKAGE git://git.sv.gnu.org/srv/git/emacs/elpa PACKAGE
+
+If you already have a packages/PACKAGE directory with a previous
+checkout, you can update it like this:
+
+   cd packages/PACKAGE
+   git pull
+
 ** Public incubation
 
 If you want to develop a package publicly prior to its first release (to