Update URL for user-guide.

basics/advection-diffusion/basics-advection-diffusion.tex

basics/helmholtz/basics-helmholtz.tex

cfs/CylinderSubsonic_NS/cfs-CylinderSubsonic_NS.tex

events/2015/Crete-SummerSchool/CreteTutorial.tex

...5/Imperial-NektarWorkshop/tutorial1-adr/tutorial1-adr.tex

flow-stability/channel/flow-stability-channel.tex

...amentals/differentiation/fundamentals-differentiation.tex

fundamentals/integration/fundamentals-integration.tex

...s/python/differentiation/fundamentals-differentiation.tex

fundamentals/python/integration/fundamentals-integration.tex

incns/taylor-green-vortex/incns-taylor-green-vortex.tex

mesh-generation/2d-naca/mesh-generation-2d-naca.tex

mesh-generation/2d-step/mesh-generation-2d-step.tex