add analysis examples to the docs

[codecov[bot]]

Codecov Report

Merging #793 (a28d942) into master (299dbee) will increase coverage by 0.00%. The diff coverage is 80.00%.

@@           Coverage Diff           @@
##           master     #793   +/-   ##
=======================================
  Coverage   97.13%   97.14%           
=======================================
  Files           4        4           
  Lines         314      315    +1     
=======================================
+ Hits          305      306    +1     
  Misses          9        9           

Impacted Files	Coverage Δ
src/root_locus.jl	97.77% <80.00%> (+0.02%)	:arrow_up:

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[JuliaControlBot]

This is an automated message. Plots were compared to references. 11/11 images have changed, see differences below. After pulling this PR, please update the reference images by creating a PR to ControlExamplePlots.jl here. Difference	Reference Image	New Image
:x: 0.048
:heavy_check_mark: 0.011
:heavy_check_mark: 0.001
:heavy_check_mark: 0.001
:heavy_check_mark: 0.006
:heavy_check_mark: 0.001
:heavy_check_mark: 0.0
:x: 0.034
:x: 0.06
:heavy_check_mark: 0.0
:warning: 0.017