CONTRIBUTING: introduce pre-commit (open-telemetry#2479)

Author: xrmx

.pre-commit-config.yaml

@@ -0,0 +1,14 @@
+repos:
+  - repo: https://github.com/psf/black-pre-commit-mirror
+    rev: 24.3.0
+    hooks:
+      - id: black
+        language_version: python3.11
+  - repo: https://github.com/pycqa/isort
+    rev: 5.12.0
+    hooks:
+      - id: isort
+  - repo: https://github.com/pycqa/flake8
+    rev: '6.1.0'
+    hooks:
+    -   id: flake8

CONTRIBUTING.md

@@ -70,6 +70,17 @@ An easier way to do so is:
 1. Run `.tox/lint-some-package/bin/black .`
 2. Run `.tox/lint-some-package/bin/isort .`
 
+Or you can call formatting and linting in one command by [pre-commit](https://pre-commit.com/):
+
+```console
+$ pre-commit
+```
+
+You can also configure it to run lint tools automatically before committing with:
+
+```console
+$ pre-commit install
+
 See
 [`tox.ini`](https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/tox.ini)
 for more detail on available tox commands.

dev-requirements.txt

@@ -17,3 +17,5 @@ codespell==2.1.0
 requests==2.31.0
 ruamel.yaml==0.17.21
 flaky==3.7.0
+pre-commit==3.7.0; python_version >= '3.9'
+pre-commit==3.5.0; python_version < '3.9'