Fix typo in the `README.md`

5 jobs for [email protected] in 6 minutes and 58 seconds
latest
Status Job ID Name Coverage
  Test
passed #238342713
ocaml:4030

00:02:46

passed #238342714
ocaml:4042

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passed #238342715
ocaml:4050

00:03:16

passed #238342716
ocaml:4060

00:03:53

passed #238342717
ocaml:4070

00:04:00