Added url to docs

[miguelmaso]

** Changelog

• Added url to docs badge in README
• Fixed images rendering in docs

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	07f4089...	main / 07f4089...
Constitutive models/Visco-elastic Ψ	25.2 ± 17 μs	27.6 ± 18 μs	0.916 ± 0.85
Constitutive models/Visco-elastic ∂Ψu	31.1 ± 2 μs	31.5 ± 2.1 μs	0.99 ± 0.094
Constitutive models/Visco-elastic ∂Ψuu	0.0622 ± 0.03 ms	0.0612 ± 0.03 ms	1.02 ± 0.7
Simulations/StaticMechanicalDirichlet	0.142 ± 0.011 s	0.135 ± 0.0069 s	1.05 ± 0.097
Simulations/StaticMechanicalNeumann	0.132 ± 0.011 s	0.134 ± 0.016 s	0.983 ± 0.14
Simulations/ViscoElastic	13.5 s	12.5 s	1.09
Tensor algebra/Cofactor	0.061 ± 0.01 μs	0.06 ± 0.001 μs	1.02 ± 0.17
Tensor algebra/Det(A)Inv(A')	0.12 ± 0.01 μs	0.13 ± 0.001 μs	0.923 ± 0.077
Tensor algebra/δδ_λ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
Tensor algebra/δδ_μ_2d	30 ± 0 ns	30 ± 0 ns	1 ± 0
time_to_load	2.88 ± 0.0052 s	2.83 ± 0.056 s	1.02 ± 0.02

Memory benchmarks

	main	07f4089...	main / 07f4089...
Constitutive models/Visco-elastic Ψ	0.542 k allocs: 0.0443 MB	0.542 k allocs: 0.0443 MB	1
Constitutive models/Visco-elastic ∂Ψu	0.593 k allocs: 0.0492 MB	0.593 k allocs: 0.0492 MB	1
Constitutive models/Visco-elastic ∂Ψuu	1.02 k allocs: 0.0839 MB	1.02 k allocs: 0.0839 MB	1
Simulations/StaticMechanicalDirichlet	1.51 M allocs: 0.108 GB	1.51 M allocs: 0.108 GB	1
Simulations/StaticMechanicalNeumann	1.48 M allocs: 0.0927 GB	1.48 M allocs: 0.0927 GB	1
Simulations/ViscoElastic	0.162 G allocs: 12.7 GB	0.162 G allocs: 12.7 GB	1
Tensor algebra/Cofactor	1 allocs: 0.0781 kB	1 allocs: 0.0781 kB	1
Tensor algebra/Det(A)Inv(A')	4 allocs: 0.25 kB	4 allocs: 0.25 kB	1
Tensor algebra/δδ_λ_2d	0 allocs: 0 B	0 allocs: 0 B
Tensor algebra/δδ_μ_2d	0 allocs: 0 B	0 allocs: 0 B
time_to_load	0.149 k allocs: 11.1 kB	0.149 k allocs: 11.1 kB	1