Amend README's git submodule instructions #220
Description
For a fresh checkout, the README's instructions for git submodule update don't suffice (it does nothing at all). One must first perform an git submodule init before the git submodule update, as follows:
$ git submodule init
Submodule 'deps/gmock' (git://github.com/cpp-netlib/gmock) registered for path 'deps/gmock'
Submodule 'deps/gtest' (git://github.com/cpp-netlib/gtest) registered for path 'deps/gtest'
Submodule 'uri' (git://github.com/cpp-netlib/uri) registered for path 'uri'
$ git submodule update
Cloning into 'deps/gmock'...
...
Submodule path 'deps/gmock': checked out '6b1759c3816d574bddde3e1725c51a811c8870e7'
Cloning into 'deps/gtest'...
...
Submodule path 'deps/gtest': checked out 'a6772271f71672e889776bfe49ec4efd9da036df'
Cloning into 'uri'...
...
Submodule path 'uri': checked out 'e3ed456dbec947765018b1dde9ede787bad91814'
(This is with Git version 1.8.0.2.)
Please amend the README instructions to mention git submodule init.