Fix typo in site settings documentation example (#6881)
Fix typo in site settings documentation example (#6881)

Lowercase `i` is used in the model definition and in other examples.
gasman/wagtail,torchbox/wagtail,zerolab/wagtail,thenewguy/wagtail,jnns/wagtail,wagtail/wagtail,thenewguy/wagtail,rsalmaso/wagtail,torchbox/wagtail,mixxorz/wagtail,thenewguy/wagtail,mixxorz/wagtail,rsalmaso/wagtail,wagtail/wagtail,jnns/wagtail,mixxorz/wagtail,zerolab/wagtail,mixxorz/wagtail,rsalmaso/wagtail,gasman/wagtail,mixxorz/wagtail,rsalmaso/wagtail,torchbox/wagtail,zerolab/wagtail,wagtail/wagtail,thenewguy/wagtail,zerolab/wagtail,wagtail/wagtail,rsalmaso/wagtail,torchbox/wagtail,jnns/wagtail,thenewguy/wagtail,gasman/wagtail,zerolab/wagtail,gasman/wagtail,jnns/wagtail,gasman/wagtail,wagtail/wagtail