docs: Add GitHub Packages installation instructions to README #6

Job	Run time
Set CI/CD metadata	7s
Commit stage / Scan secrets	2m 16s
Commit stage / Check Markdown format	16s
Commit stage / Scan dependencies	46s
Commit stage / Check file format	19s
Commit stage / Check English usage	9s
Commit stage / Count lines of code	11s
Commit stage / Lint Terraform	8s
Test stage	0s
Build stage	-1s
Acceptance stage	0s
	4m 11s

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