Added top-level README file.

README

+These are the work-in-progress files for the project "Anpassning av
+GNU Nettle för inbyggda system", funded by Internetfonden for spring
+2013.
+
+There are two main objectives for the project:
+
+1. Implement digital signatures based on elliptic curves.
+
+2. Optimize important crypto primitives for the ARM architecture.
+
+The "ecc" subdirectory contains the work-in-progress ECC
+implementation. I try to keep the code working, but it is very crude
+in some corners. When matured, it will be integrated into the main
+Nettle repository.
+
+ARM assembly files will probably not be maintained in this repository,
+but integrated in the Nettle repository more incrementally.
+
+The doc subdirectory contains various working notes.
+
+The benchmark subdirectory collects benchmarking figures for various
+stages of the project.