Added README file.

README.rst

+bundle-certs
+############
+
+A shell script to bundle SSL certificates in the correct order.
+
+Installation
+------------
+
+This script can be used in 2 ways. The 1st is copying to
+:code:`/usr/local/bin/bundle_certs`, marking as executable and calling the
+script. The 2nd is copying the file to somewhere under you home directory and
+sourcing it in your shell's rc file (like .bashrc, .kshrc etc.).
+
+Usage
+-----
+
+Call the script/ function with the list of certificates you want to order, for
+example:
+
+.. code:: shell
+
+    bundle_certs *.crt