[DOC] Tweaks for StringIO.closed_write? #506

Job	Run time
ruby-versions / Generate Ruby versions	4s
ubuntu-24.04 3.1	17s
ubuntu-24.04 2.7	47s
ubuntu-24.04 head	15s
ubuntu-24.04 3.0	13s
ubuntu-24.04 jruby-head	1m 1s
ubuntu-24.04 3.3	29s
ubuntu-24.04 3.4	13s
ubuntu-22.04 3.1	21s
ubuntu-22.04 2.7	41s
ubuntu-22.04 3.0	16s
ubuntu-24.04 truffleruby-head	24s
ubuntu-22.04 3.2	27s
ubuntu-24.04 debug	25s
ubuntu-24.04 3.2	29s
ubuntu-22.04 debug	24s
ubuntu-22.04 3.3	24s
ubuntu-22.04 3.4	20s
ubuntu-22.04 jruby-head	1m 9s
ubuntu-22.04 truffleruby-head	30s
ubuntu-22.04 head	18s
	9m 27s

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