Fix formatting of warning block in `README.md` #674

Job	Run time
Linux - bootstrap-ubi.sh - no tag	2s
Linux - bootstrap-ubi.sh - v0.1.1	4s
Alpine Linux (ash) - bootstrap-ubi.sh - no tag	6s
Alpine Linux (ash) - bootstrap-ubi.sh - v0.1.1	11s
macOS - bootstrap-ubi.sh - no tag	6s
macOS - bootstrap-ubi.sh - v0.1.1	6s
Windows - bootstrap-ubi.ps1 - no tag	16s
	51s

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