Simplify YML files

[miguelmaso]

Changelog

• Removed deprecated statements
• Stable docs badge point to stable

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	337bb91...	main / 337bb91...
Constitutive models/Visco-elastic Ψ	25.5 ± 16 μs	25.3 ± 17 μs	1.01 ± 0.93
Constitutive models/Visco-elastic ∂Ψu	0.0317 ± 0.0021 ms	31.1 ± 1.8 μs	1.02 ± 0.09
Constitutive models/Visco-elastic ∂Ψuu	0.0621 ± 0.029 ms	0.0612 ± 0.03 ms	1.01 ± 0.68
Simulations/StaticMechanicalDirichlet	0.132 ± 0.0078 s	0.133 ± 0.0068 s	0.99 ± 0.077
Simulations/StaticMechanicalNeumann	0.13 ± 0.013 s	0.129 ± 0.012 s	1 ± 0.14
Simulations/ViscoElastic	12.3 s	12.1 s	1.02
Tensor algebra/Cofactor	0.06 ± 0.01 μs	0.06 ± 0.01 μs	1 ± 0.24
Tensor algebra/Det(A)Inv(A')	0.12 ± 0.01 μs	0.12 ± 0.01 μs	1 ± 0.12
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	2.78 ± 0.044 s	2.76 ± 0.01 s	1.01 ± 0.016

Memory benchmarks

	main	337bb91...	main / 337bb91...
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	0.159 k allocs: 11.6 kB	0.964