Remove linkcheck from the dev docs

Author: jtpio

docs/source/dev_docs.md

@@ -42,12 +42,6 @@ make html
 After that, the generated HTML files will be available at
 `build/html/index.html`. You may view the docs in your browser.
 
-You can automatically check if all hyperlinks are still valid:
-
-```bash
-make linkcheck
-```
-
 Windows users can find `make.bat` in the `docs` folder.
 
 You should also have a look at the [Project Jupyter Documentation Guide](https://jupyter.readthedocs.io/en/latest/contrib_docs/index.html).