[DOC] Doc for StringIO#read (#197) #636

Job	Run time
ruby-versions / Generate Ruby versions	3s
ubuntu-24.04 3.2	19s
ubuntu-24.04 3.3	19s
ubuntu-24.04 3.0	19s
ubuntu-22.04 3.2	20s
ubuntu-24.04 debug	27s
ubuntu-24.04 truffleruby-head	35s
ubuntu-22.04 3.1	16s
ubuntu-22.04 3.3	18s
ubuntu-24.04 head	13s
ubuntu-22.04 3.0	16s
ubuntu-24.04 jruby-head	1m 3s
ubuntu-22.04 debug	25s
ubuntu-24.04 3.1	12s
ubuntu-24.04 2.7	45s
ubuntu-22.04 truffleruby-head	29s
ubuntu-22.04 jruby-head	1m 5s
ubuntu-22.04 2.7	41s
ubuntu-22.04 head	12s
ubuntu-24.04 3.4	17s
ubuntu-22.04 3.4	17s
	8m 51s

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