Not doing so results in the following error :

CMake Error at Externals/cubeb/CMakeLists.txt:30 (message):
  Could not find sanitizers-cmake: run

  	git submodule update --init --recursive

  in base git checkout

As the advice is correct, update readme with the correct command.

Enforce minimum supported versions of GCC and Clang

The old URL redirects to the new URL for now, but apparently it will
stop doing that in a few months. Let's update it in the Readme.

We already have a minimum required version of MSVC

This unhides the dolphin-emu and dolphin-tool convert usage, which were hidden because the backticks preceding them were not on their own line.

Fix Transifex link and update formatting.