[3.2.x] Fixed typo in docs/intro/reusable-apps.txt.
[3.2.x] Fixed typo in docs/intro/reusable-apps.txt.

Backport of 475cffd1d64c690cdad16ede4d5e81985738ceb4 from main

koordinates/django,koordinates/django,koordinates/django,koordinates/django