[DOC] Class doc for StringIO #580

Job	Run time
ruby-versions / Generate Ruby versions	5s
ubuntu-24.04 3.1	18s
ubuntu-24.04 3.2	16s
ubuntu-24.04 2.7	57s
ubuntu-24.04 3.0	13s
ubuntu-24.04 3.4	24s
ubuntu-24.04 debug	34s
ubuntu-24.04 3.3	18s
ubuntu-24.04 head	18s
ubuntu-22.04 2.7	44s
ubuntu-22.04 3.3	19s
ubuntu-22.04 3.1	13s
ubuntu-24.04 truffleruby-head	24s
ubuntu-22.04 3.2	23s
ubuntu-22.04 3.4	19s
ubuntu-24.04 jruby-head	1m 16s
ubuntu-22.04 3.0	20s
ubuntu-22.04 head	16s
ubuntu-22.04 debug	40s
ubuntu-22.04 jruby-head	1m 15s
ubuntu-22.04 truffleruby-head	24s
ruby-versions / Generate Ruby versions	5s
ubuntu-24.04 2.7	57s
ubuntu-24.04 3.2	16s
ubuntu-24.04 3.1	18s
ubuntu-24.04 3.0	13s
ubuntu-24.04 3.4	24s
ubuntu-24.04 3.3	18s
ubuntu-24.04 debug	34s
ubuntu-22.04 3.1	13s
ubuntu-24.04 head	18s
ubuntu-22.04 3.3	19s
ubuntu-22.04 3.0	20s
ubuntu-22.04 3.2	23s
ubuntu-24.04 truffleruby-head	18s
ubuntu-22.04 2.7	44s
ubuntu-24.04 jruby-head	1m 16s
ubuntu-22.04 debug	40s
ubuntu-22.04 3.4	19s
ubuntu-22.04 truffleruby-head	24s
ubuntu-22.04 head	16s
ubuntu-22.04 jruby-head	1m 15s
ruby-versions / Generate Ruby versions	5s
ubuntu-24.04 2.7	57s
ubuntu-24.04 head	18s
ubuntu-24.04 debug	34s
ubuntu-22.04 3.0	20s
ubuntu-24.04 jruby-head	1m 16s
ubuntu-24.04 3.0	13s
ubuntu-24.04 3.2	16s
ubuntu-24.04 3.3	18s
ubuntu-22.04 3.2	23s
ubuntu-24.04 3.1	18s
ubuntu-24.04 truffleruby-head	30s
ubuntu-22.04 truffleruby-head	33s
ubuntu-24.04 3.4	24s
ubuntu-22.04 3.3	19s
ubuntu-22.04 2.7	44s
ubuntu-22.04 3.1	13s
ubuntu-22.04 3.4	19s
ubuntu-22.04 head	16s
ubuntu-22.04 debug	40s
ubuntu-22.04 jruby-head	1m 15s
	29m 57s

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