[1.8.x] Fixed typo in docs/ref/templates/builtins.txt
[1.8.x] Fixed typo in docs/ref/templates/builtins.txt

Backport of 48ddc66219deaac2aa5fa3d2cb0f420404d6b8ec from master

h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,pquentin/django,h4r5h1t/django-hauthy,pquentin/django,h4r5h1t/django-hauthy,pquentin/django