[Docs] Fix references

docs/admin/10_install.rst

@@ -252,6 +252,5 @@ Finally, bring the stack up using:
 AlekSIS will be reachable on port 80 if you forgot to configure the environment.
 You are responsible for adding a reverse proxy like nginx providing TLS, etc.
 
-.. _Dynaconf: https://dynaconf.readthedocs.io/en/latest/
 .. _Let's Encrypt: https://certbot.eff.org/instructions
 .. _PyPI: https://pypi.org

docs/admin/32_tasks.rst

@@ -24,3 +24,5 @@ is currently only possible through the Django Admin backend, under
 Under the *Periodic Tasks* app, you can define schedules and tasks. The names
 of tasks you can add manually are documented in the respective sections
 of the manual.
+
+.. _Celery: https://celeryproject.org/