Update docs

[rodrigomha]

Track. This will not cover developer guide and testing guidelines

• Loads
• AVR
• PSS
• Others (TODO what is missing)

[github-actions]

Performance Results

Version	Precompile Time
Master	14.381024201
This Branch	14.086977891

Version	Execute Time
Master-Build ResidualModel	14.638899815
Master-Execute ResidualModel	41.312748339
Master-Build MassMatrixModel	9.003079914
Master-Execute MassMatrixModel	52.558942928
This Branch-Build ResidualModel	15.081989747
This Branch-Execute ResidualModel	43.824762338
This Branch-Build MassMatrixModel	9.439009964
This Branch-Execute MassMatrixModel	52.362802584

ResidualModel and MassMatrixModel performance results should be compared between versions and not between models due to the execution order of the tests

[codecov]

Codecov Report

Merging #243 (024d730) into master (159552e) will increase coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #243      +/-   ##
==========================================
+ Coverage   90.44%   90.57%   +0.13%     
==========================================
  Files          63       64       +1     
  Lines        6093     6337     +244     
==========================================
+ Hits         5511     5740     +229     
- Misses        582      597      +15     

Flag	Coverage Δ
unittests	90.57% <ø> (+0.13%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/base/simulation_model.jl	0.00% <0.00%> (-100.00%)	⬇️
src/models/dynline_model.jl	41.93% <0.00%> (-58.07%)	⬇️
src/models/common_controls.jl	81.33% <0.00%> (-6.60%)	⬇️
src/base/branch_wrapper.jl	53.57% <0.00%> (-3.58%)	⬇️
src/base/perturbations.jl	58.42% <0.00%> (-3.32%)	⬇️
src/base/small_signal.jl	80.80% <0.00%> (-1.60%)	⬇️
src/base/simulation_inputs.jl	93.54% <0.00%> (-0.29%)	⬇️
src/base/simulation_initialization.jl	84.07% <0.00%> (-0.23%)	⬇️
src/base/jacobian.jl	95.58% <0.00%> (-0.19%)	⬇️
src/base/simulation.jl	89.55% <0.00%> (-0.06%)	⬇️
... and 21 more

[jd-lara]

preview link https://nrel-siip.github.io/PowerSimulationsDynamics.jl/previews/PR243/

[jd-lara]

We need to update some of the figures with updated ones, specially the software structure

[rodrigomha]

The following PR is related with #233 but developer and testing guidelines will be addressed in a future PR.