Added README.chromium file.

The local README.chromium includes a description of the project and
release version it is based on.

BUG=chromium:474769
TEST=None

Change-Id: I5f8123984c820c64e7cbe5a9cc1642061aa2ed1c

README.chromium

+Homepage: http://www.daemonology.net/bsdiff/
+Version: 4.3.1
+License: BSD-2
+
+Description:
+
+Binary diff/patch utility.
+
+bsdiff and bspatch are tools for building and applying patches to binary
+files. By using suffix sorting and taking advantage of how executable files
+change, bsdiff routinely produces binary patches 50-80% smaller than those
+produced by Xdelta, and 15% smaller than those produced by .RTPatch.