Add descriptions to the tox environments. Closes #91.

tox.ini

@@ -1,4 +1,5 @@
 [testenv]
+description = perform primary checks (tests, style, types, coverage)
 deps =
 setenv =
 	PYTHONWARNDEFAULTENCODING = 1
@@ -9,6 +10,7 @@ extras =
 	testing
 
 [testenv:diffcov]
+description = run tests and check that diff from main is covered
 deps =
 	diff-cover
 commands =
@@ -17,6 +19,7 @@ commands =
 	diff-cover coverage.xml --compare-branch=origin/main --fail-under=100
 
 [testenv:docs]
+description = build the documentation
 extras =
 	docs
 	testing
@@ -26,6 +29,7 @@ commands =
 	python -m sphinxlint
 
 [testenv:finalize]
+description = assemble changelog and tag a release
 skip_install = True
 deps =
 	towncrier
@@ -36,6 +40,7 @@ commands =
 
 
 [testenv:release]
+description = publish the package to PyPI and GitHub
 skip_install = True
 deps =
 	build