Add a brief README file for blazecli #341

Job	Run time
Benchmark	7m 30s
Generate documentation	24s
Check generated C header	40s
Build [ubuntu-latest, 1.63.0, dev, ]	1m 53s
Build [ubuntu-latest, 1.63.0, release, ]	2m 26s
Build [ubuntu-latest, stable, dev, ]	33s
Build [ubuntu-latest, stable, release, ]	38s
Build [macos-latest, 1.63.0, dev, ]	2m 31s
Build [macos-latest, 1.63.0, release, ]	2m 57s
Build [macos-latest, stable, dev, ]	57s
Build [macos-latest, stable, release, ]	1m 14s
Build [ubuntu-latest, stable, dev, --no-default-features]	19s
Lint with clippy	58s
No-op rebuilds	57s
Check code formatting	13s
Test and coverage	2m 38s
Test with release build	2m 50s
Test with address sanitizer	3m 46s
Test with leak sanitizer	3m 17s
	36m 41s

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