refactor: merge tox and docs improvements from mdformat-admon

CONTRIBUTING.md

@@ -5,7 +5,7 @@ This package utilizes [flit](https://flit.readthedocs.io) as the build engine, a
 To install these development dependencies:
 
 ```bash
-pip install tox
+pipx install tox
 ```
 
 To run the tests:

tox.ini

@@ -3,17 +3,17 @@ envlist =
     py{310}-cov
     py{37}-recommended
     py{310}-pre-commit
-    py{37,310}-hook
+    py{37}-hook
 isolated_build = True
 skip_missing_interpreters = False
 
-[testenv:py{310}]
+[testenv:py{37}]
 extras = test
 commands = pytest {posargs} --ff --nf -vv
 
 [testenv:py{310}-cov]
 extras = test
-commands = pytest --cov={envsitepackagesdir}/mdformat_mkdocs {posargs}
+commands = pytest --cov=mdformat_mkdocs {posargs}
 
 [testenv:py{37}-recommended]
 extras = recommended,test
@@ -23,7 +23,7 @@ commands = pytest {posargs} --ff --nf -vv --exitfirst
 extras = dev
 commands = pre-commit run {posargs:--all-files}
 
-[testenv:py{37,310}-hook]
+[testenv:py{37}-hook]
 extras = dev
 commands = pre-commit run --config .pre-commit-test.yaml {posargs:--all-files --verbose --show-diff-on-failure}