ecs: Add internal doc and cfn template for ECS Prometheus

[pingleig]

Description:

Only apply to Container Insights ECS Prometheus

• Add cfn template
• Add doc for some tricky parts and future work

btw: user doc will be another PR aws-otel/aws-otel.github.io#128 https://github.com/aws-otel/aws-otel.github.io draft is in https://github.com/pingleig/aws-otel.github.io/tree/ecssd-draft/src/docs/getting-started/container-insights

Link to tracking Issue:

• [feature][prometheus] ECS service discovery extension for prometheus #412

Testing:

N/A

Documentation:

This is a doc PR

[codecov-commenter]

Codecov Report

Merging #560 (9fd148e) into main (3910907) will increase coverage by 1.55%.
The diff coverage is n/a.

❗ Current head 9fd148e differs from pull request most recent head d94bed9. Consider uploading reports for the commit d94bed9 to get more accurate results

@@            Coverage Diff             @@
##             main     #560      +/-   ##
==========================================
+ Coverage   61.82%   63.38%   +1.55%     
==========================================
  Files           8        8              
  Lines         186      213      +27     
==========================================
+ Hits          115      135      +20     
- Misses         55       62       +7     
  Partials       16       16              

Impacted Files	Coverage Δ
tools/version/build.go	100.00% <0.00%> (ø)
pkg/config/config_factory.go	100.00% <0.00%> (ø)
pkg/extraconfig/container.go	0.00% <0.00%> (ø)
pkg/userutils/set_uid_gid.go	0.00% <0.00%> (ø)
pkg/defaultcomponents/defaults.go	80.39% <0.00%> (+1.22%)	⬆️
pkg/extraconfig/extraconfig.go	88.57% <0.00%> (+1.47%)	⬆️
pkg/userutils/userutil_linux.go	26.08% <0.00%> (+1.89%)	⬆️
pkg/logger/logger.go	80.55% <0.00%> (+3.13%)	⬆️

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[mxiamxia]

thanks