Update wiki "Installation via Github Release"

[vevilo]

Some of the commands need updated to be able to install v0.10.0 release (not sure about earlier releases).

Here are the updated lines:
Download release from mwalib github releases. (Where X.Y.Z is the current release version)
wget "https://github.com/MWATelescope/mwalib/releases/download/vX.Y.Z/mwalib-vX.Y.Z-linux_x86_64.tar.gz" -O mwalib.tar.gz

Install
sudo cp mwalib/libmwalib.* /usr/local/lib
sudo cp mwalib/mwalib.h /usr/local/include

[gsleap]

Thanks @vevilo for the update! I've made the changes to the wiki now.