Organize README.ja.rdoc #97

Job	Run time
ruby-versions / Generate Ruby versions	2s
test (2.5, ubuntu-latest)	27s
test (2.5, windows-latest)	1m 58s
test (2.6, ubuntu-latest)	28s
test (2.6, macos-latest)	35s
test (2.6, windows-latest)	2m 33s
test (2.7, ubuntu-latest)	27s
test (2.7, macos-latest)	30s
test (2.7, windows-latest)	3m 22s
test (3.0, ubuntu-latest)	16s
test (3.0, macos-latest)	18s
test (3.0, windows-latest)	2m 17s
test (3.1, ubuntu-latest)	15s
test (3.1, macos-latest)	19s
test (3.1, windows-latest)	1m 29s
test (3.2, ubuntu-latest)	16s
test (3.2, macos-latest)	21s
test (3.2, windows-latest)	1m 37s
test (3.3, ubuntu-latest)	16s
test (3.3, macos-latest)	23s
test (3.3, windows-latest)	3m 30s
test (head, ubuntu-latest)	16s
test (head, macos-latest)	20s
test (head, windows-latest)	1m 4s
test (jruby, ubuntu-latest)	4m 22s
test (jruby-head, ubuntu-latest)	4m 27s
test (truffleruby, ubuntu-latest)	1m 36s
test (truffleruby-head, ubuntu-latest)	1m 49s
	35m 33s

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