[DOC] Small grammar/formatting fix #1844

Job	Run time
RuboCop	32s
specs (ubuntu, 3.0.6)	1m 34s
specs (ubuntu, 3.1.4)	1m 33s
specs (ubuntu, 3.2.2)	1m 31s
specs (ubuntu, 3.3.0)	1m 28s
specs (macos, 3.0.6)	1m 18s
specs (macos, 3.1.4)	1m 23s
specs (macos, 3.2.2)	1m 36s
specs (macos, 3.3.0)	1m 39s
specs (windows, 3.0.6)	3m 41s
specs (windows, 3.1.4)	5m 32s
specs (windows, 3.2.2)	4m 3s
specs (windows, 3.3.0)	5m 31s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 30s
	32m 51s

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