Products.ERP5.ERP5Site: Fix docstring typo

5 jobs for master in 0 seconds (queued for 1 second)
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

01:12:28

failed ERP5.UnitTest-Master

01:52:54

failed ERP5.UnitTest-Master.Medusa

02:06:06

passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python3

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