Add baby walkthrough for ECS deployment via GitHub Actions on master push

[Andrew-Chen-Wang]

Review the Contributing Guidelines

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Describe Why This Is Awesome

Why is this awesome?

It's a guide + ready-to-go code for ECS blue/green deployment using GitHub Actions + CodeDeploy, and your code is deployed automatically with GitHub actions on push from master.

There are almost no good walkthroughs for ECS deployment. I wrote a complete walkthrough, everything filled out completely with justification/explanations, with code ready to go (noted what files are necessary if you're not using Django of course). It includes an nginx reverse proxy configuration behind an ALB with Route 53 + ACM and all necessary files included with its content. Pretty much anything you need for an ECS deployment is here.

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[codecov-commenter]

Codecov Report

Merging #194 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #194   +/-   ##
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  Coverage   96.62%   96.62%           
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  Files           4        4           
  Lines          89       89           
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  Hits           86       86           
  Misses          3        3