Fix public issue #53: Update the README to the API we actually open-sourced
with.

R=sanjay


git-svn-id: https://snappy.googlecode.com/svn/trunk@52 03e5f5b5-db94-4691-08a0-1a8bf15f6143

README

diff --git a/README b/README
index df8f0e1..3bc8888 100644
--- a/README
+++ b/README
@@ -76,11 +76,11 @@
 
 There are many ways to call Snappy, but the simplest possible is
 
-  snappy::Compress(input, &output);
+  snappy::Compress(input.data(), input.size(), &output);
 
 and similarly
 
-  snappy::Uncompress(input, &output);
+  snappy::Uncompress(input.data(), input.size(), &output);
 
 where "input" and "output" are both instances of std::string.