docs(bindings/ruby): add documentation for Ruby binding (#5629) #2511

Job	Run time
build_all_features	4m 48s
build_all_platforms (ubuntu-latest)	2m 30s
build_all_platforms (macos-latest)	3m 1s
build_default_features (ubuntu-latest)	39s
build_all_platforms (windows-latest)	5m 47s
build_under_wasm	57s
build_default_features (macos-latest)	1m 3s
check_clippy	3m 31s
build_default_features (windows-latest)	2m 51s
check_docs	3m 53s
check_msrv	36s
unit	7m 4s
	36m 40s

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