Add example of updating a page within after_create_page (#6373)
Add example of updating a page within after_create_page (#6373)

This update intends to add the answer I got on my slack support request (https://wagtailcms.slack.com/archives/C81FGJR2S/p1599209092087000).

mixxorz/wagtail,wagtail/wagtail,thenewguy/wagtail,wagtail/wagtail,rsalmaso/wagtail,wagtail/wagtail,kaedroho/wagtail,FlipperPA/wagtail,rsalmaso/wagtail,torchbox/wagtail,mixxorz/wagtail,jnns/wagtail,gasman/wagtail,zerolab/wagtail,rsalmaso/wagtail,jnns/wagtail,thenewguy/wagtail,gasman/wagtail,kaedroho/wagtail,jnns/wagtail,torchbox/wagtail,torchbox/wagtail,thenewguy/wagtail,mixxorz/wagtail,rsalmaso/wagtail,FlipperPA/wagtail,FlipperPA/wagtail,zerolab/wagtail,thenewguy/wagtail,torchbox/wagtail,mixxorz/wagtail,zerolab/wagtail,thenewguy/wagtail,zerolab/wagtail,gasman/wagtail,kaedroho/wagtail,kaedroho/wagtail,FlipperPA/wagtail,mixxorz/wagtail,wagtail/wagtail,jnns/wagtail,kaedroho/wagtail,gasman/wagtail,rsalmaso/wagtail,wagtail/wagtail,gasman/wagtail,zerolab/wagtail