Adjusted Docker badge [ci skip]

README.md

@@ -10,7 +10,7 @@
   [gitter-link]: https://gitter.im/squidfunk/mkdocs-material
   [codacy-image]: https://api.codacy.com/project/badge/Grade/fe07aa1fa91d453cb69711d3885c5d7e
   [codacy-link]: https://www.codacy.com/app/squidfunk/mkdocs-material?utm_source=github.com&utm_medium=referral&utm_content=squidfunk/mkdocs-material&utm_campaign=Badge_Grade
-  [docker-image]: https://img.shields.io/docker/automated/squidfunk/mkdocs-material.svg
+  [docker-image]: https://img.shields.io/docker/pulls/squidfunk/mkdocs-material.svg
   [docker-link]: https://hub.docker.com/r/squidfunk/mkdocs-material/
   [pypi-image]: https://img.shields.io/pypi/v/mkdocs-material.svg
   [pypi-link]: https://pypi.python.org/pypi/mkdocs-material