[linux] - small change to the Wiki instructions when cloning the project

[BielBdeLuna]

I know OpenXRay is all-together the xray-16, the xray-15, and the xray repositories. But I propose that in the WIKI instructions, on how to compile in Linux, add this little change:

git clone https://github.com/OpenXRay/xray-16.git OpenXRay --recurse-submodules

so all the code goes to the folder OpenXRay instead of folder xray-16

and so make other pertinent changes in the instructions to reflect that like:

cd OpenXRay && mkdir bin && cd bin