Add a README file

This provides a brief introduction to the project, and information re:
how to submit patches.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

README.txt

@@ -0,0 +1,34 @@
+Introduction
+============
+
+This project provides a tool which compiles BCT (Boot Configuration Table)
+images to place into the boot flash of a Tegra-based device.
+
+The tool will either:
+
+a) Compile a textual representation of a BCT into a binary image.
+
+b) Generate an entire boot image from a previously compiled BCT and a
+   bootloader binary.
+
+Submitting Changes
+==================
+
+To submit patches to this project, please use the following commands:
+
+* git format-patch --subject-prefix="cbootimage PATCH"
+
+  Creates a patch file from your git commit.
+
+* git send-email --to linux-tegra@vger.kernel.org *.patch
+
+  Sends the patch by email to the Tegra mailing list.
+
+Even though the primary upstream repository for this project is hosted on
+github, contributions aren't accepted via github pull requests. Github pull
+requests would bypass public code review on the project mailing list.
+
+Patches should be signed off (include a signed-off-by line) to indicate your
+acceptance of the code's license (see COPYING and the license header in each
+file). See http://developercertificate.org/ for details of what signed-off-by
+implies.