docs(traffic_ligtht_classifier): update document for CNN model customization

[ktro2828]

Description

Currently, in autoware, we recommend to use open-mmlab/mmclassification for re-training CNN classifier.
Therefore I updated documents to train CNN models and apply them to traffic light cnn classifier node.
After this PR is merged, I will add the link of this document to the Autoware documentaion, as disscussed in this PR.

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[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (7f064da) 11.93% compared to head (2be7592) 11.94%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3037   +/-   ##
=======================================
  Coverage   11.93%   11.94%           
=======================================
  Files        1321     1321           
  Lines       91936    91903   -33     
  Branches    24522    24511   -11     
=======================================
  Hits        10976    10976           
+ Misses      69602    69569   -33     
  Partials    11358    11358           

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <ø> (?)
total	11.94% <ø> (+<0.01%)	⬆️	Carriedforward from 7f064da

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
...havior_path_planner/behavior_path_planner_node.hpp	0.00% <ø> (ø)
...er/scene_module/lane_change/lane_change_module.hpp	0.00% <ø> (ø)
...or_path_planner/src/behavior_path_planner_node.cpp	0.14% <ø> (ø)
...rc/scene_module/lane_change/lane_change_module.cpp	0.00% <ø> (ø)
...erception/traffic_light_classifier/src/nodelet.cpp	0.00% <0.00%> (ø)

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[yukkysaito]

LGTM