[web] Added benchmark PDFs to repo via git-lfs.

.gitattributes

web/content/docs/benchmarks/hydro-mechanics/LIE_HM.pdf

web/content/docs/benchmarks/hydro-thermal/HT-Process.pdf

...ntent/docs/benchmarks/hydro-thermal/constant-viscosity.md

web/content/docs/benchmarks/richards-flow/richards-2.pdf

web/content/docs/benchmarks/richards-flow/richards-flow.md

...tent/docs/benchmarks/small-deformations/Circular_hole.pdf

...s/benchmarks/small-deformations/LIE_small_deformation.pdf

...content/docs/benchmarks/small-deformations/Plasticity.pdf

...hmarks/small-deformations/lie-m-linear-single-fracture.md

web/content/docs/benchmarks/small-deformations/lubby2.pdf

...rks/small-deformations/mechanics-linear-disc-with-hole.md

...rks/small-deformations/mechanics-lubby2-shear-traction.md

...small-deformations/mechanics-plasticity-single-surface.md

web/content/docs/benchmarks/two-phase-flow/MoMaS.pdf

web/content/docs/benchmarks/two-phase-flow/momas.md