Add dependencies for installation on Ubuntu

[camillem]

Hi,

On Ubuntu 20.04 LTS, you also need to sudo apt install golang-goprotobuf-dev
So on https://qmstr.org/documentation/introduction/installation/ I would suggest to change:

sudo apt install golang protobuf-compiler
into
sudo apt install golang protobuf-compiler golang-goprotobuf-dev

Also, it may help inattentive readers (like me), if the page would explicitly state that you need root/sudo rights to build/install the client .

sudo make install_qmstr_client

Thanks,
Camille