Revert "temp: disable linkcheck"

This reverts commit 55d15c0.

Author: VeckoTheGecko

.readthedocs.yaml

@@ -11,7 +11,7 @@ build:
   jobs:
     pre_build:
       - pip install .
-      # - sphinx-build -b linkcheck docs/ _build/linkcheck
+      - sphinx-build -b linkcheck docs/ _build/linkcheck
       - sphinx-apidoc -o docs/api/ --module-first --no-toc --force src/virtualship
 
 conda: