misc: add codestyle files/notes (#61513)

.git-blame-ignore-revs

@@ -0,0 +1,2 @@
+# codestyle: add black, isort, pyupgrade (#61513)
+6006c9655793c895ce896c18770620e79a315038

.pre-commit-config.yaml

@@ -0,0 +1,18 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+-   repo: https://github.com/psf/black
+    rev: 21.10b0
+    hooks:
+    - id: black
+      args: ['--target-version', 'py37', '--skip-string-normalization', '--line-length', '110']
+-   repo: https://github.com/PyCQA/isort
+    rev: 5.7.0
+    hooks:
+    - id: isort
+      args: ['--profile', 'black', '--line-length', '110']
+-   repo: https://github.com/asottile/pyupgrade
+    rev: v2.20.0
+    hooks:
+    - id: pyupgrade
+      args: ['--keep-percent-format', '--py37-plus']

README

@@ -8,6 +8,28 @@ Installation
 
 Install with `pip install authentic2-cut`
 
+Code Style
+==========
+
+black is used to format the code, using thoses parameters:
+
+    black --target-version py37 --skip-string-normalization --line-length 110
+
+There is .pre-commit-config.yaml to use pre-commit to automatically run black
+before commits. (execute `pre-commit install` to install the git hook.)
+
+isort is used to format the imports, using those parameter:
+
+    isort --profile black --line-length 110
+
+pyupgrade is used to automatically upgrade syntax, using those parameters:
+
+    pyupgrade --keep-percent-format --py37-plus
+
+There is .pre-commit-config.yaml to use pre-commit to automatically run black,
+isort and pyupgrade before commits. (execute `pre-commit install` to install
+the git hook.)
+
 Settings
 ========