Set release branch version to 0.4.0.

c++/configure.ac

 ## Process this file with autoconf to produce configure.
 
-AC_INIT([Capn Proto],[0.4.0-rc3],[capnproto@googlegroups.com],[capnproto-c++])
+AC_INIT([Capn Proto],[0.4.0],[capnproto@googlegroups.com],[capnproto-c++])
 
 AC_CONFIG_SRCDIR([src/capnp/layout.c++])
 AC_CONFIG_AUX_DIR([build-aux])

doc/install.md

@@ -67,9 +67,9 @@ the upcoming CTPs (the November 2013 CTP is almost there).
 
 You may download and install the release version of Cap'n Proto like so:
 
-<pre><code>curl -O <a href="http://capnproto.org/capnproto-c++-0.0.0.tar.gz">http://capnproto.org/capnproto-c++-0.0.0.tar.gz</a>
-tar zxf capnproto-c++-0.0.0.tar.gz
-cd capnproto-c++-0.0.0
+<pre><code>curl -O <a href="http://capnproto.org/capnproto-c++-0.4.0.tar.gz">http://capnproto.org/capnproto-c++-0.4.0.tar.gz</a>
+tar zxf capnproto-c++-0.4.0.tar.gz
+cd capnproto-c++-0.4.0
 ./configure
 make -j6 check
 sudo make install</code></pre>