[WIP] Update documentation

[rodrigomha]

Update documentation for LITS 0.4.0.

Updated the model. Added a new SRF part to describe the reference transformations.
To do:

• Update Example 01
• Update Example 02

[codecov]

Codecov Report

Merging #65 into jd/update_test_files will increase coverage by 17.46%.
The diff coverage is 97.05%.

@@                    Coverage Diff                    @@
##           jd/update_test_files      #65       +/-   ##
=========================================================
+ Coverage                 75.25%   92.72%   +17.46%     
=========================================================
  Files                        30       44       +14     
  Lines                      1075     1827      +752     
=========================================================
+ Hits                        809     1694      +885     
+ Misses                      266      133      -133     

Impacted Files	Coverage Δ
src/LITS.jl	100.00% <ø> (ø)
src/models/device.jl	100.00% <ø> (ø)
src/models/generator_models/pss_models.jl	100.00% <ø> (+84.61%)	⬆️
src/models/generator_models/shaft_models.jl	100.00% <ø> (ø)
src/models/system.jl	78.18% <66.66%> (-21.82%)	⬇️
src/base/file_system.jl	80.00% <80.00%> (ø)
src/base/simulation_initialization.jl	83.78% <83.78%> (ø)
src/base/simulation.jl	84.07% <90.90%> (-10.35%)	⬇️
src/initialization/generator_components/init_tg.jl	96.61% <96.61%> (ø)
src/utils/plot_utils.jl	97.95% <97.29%> (-2.05%)	⬇️
... and 43 more