Add tox env to build the docs.

Author: icemac

tox.ini

@@ -12,6 +12,7 @@ max-line-length = 88
 envlist =
     linting
     py{39,310,311,312,313,py3}-pytest{74,80,81,82,83,main}
+    docs
 minversion = 4.0
 
 [testenv]
@@ -30,3 +31,10 @@ basepython = python3
 commands = pre-commit run --all-files --show-diff-on-failure {posargs:}
 deps = pre-commit>=1.11.0
 skip_install = True
+
+[testenv:docs]
+basepython = python3
+skip_install = True
+deps = -r docs/requirements.txt
+commands =
+    sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html