Fix a typo and Markdown heading levels

CONTRIBUTING.md

@@ -1,4 +1,4 @@
-## Contributing
+# Contributing
 
 The best way to contribute to the MLCommons is to get involved with one of our many project communities. You find more information about getting involved with MLCommons [here](https://mlcommons.org/en/get-involved/#getting-started). 
 

datasets/README.md

@@ -1,6 +1,8 @@
+# Dataset Definitions
+
 This directory contains definitions of datasets (one sub-directory per version and per dataset).
 
-```
+```text
 datasets
 |_ 0.8                 # Croissant major version (standard)
   |_ titanic

editor/README.md

@@ -22,7 +22,7 @@ You can debug the tests in Github Actions because failed screenshots are uploade
 
 You may need to install [`libmagic`](https://pypi.org/project/python-magic).
 
-# Create a custom component
+## Create a custom component
 
 Custom components are in `components/`.
 
@@ -102,7 +102,7 @@ st.write(node)
 
 - Build the JavaScript locally.
 
-```
+```bash
 cd components/tree/frontend/
 npm run build
 ```
@@ -114,7 +114,7 @@ npm run build
 
 Change `TAG` below and execute the following commands:
 
-```
+```bash
 TAG=0.0.1
 IMAGE=croissant-editor
 docker build -t ${IMAGE} .

health/README.md

@@ -1,6 +1,6 @@
 # Croissant 🥐 Online Health
 
-This project aims at monitoring the health of the online Croissant ecocystem
+This project aims at monitoring the health of the online Croissant ecosystem
 by crawling online JSON-LD files shared across repositories.
 
 It contains:

python/mlcroissant/README.md

@@ -34,6 +34,7 @@ sudo apt-get install python3-dev graphviz libgraphviz-dev pkg-config
 ```
 
 ### Conda installation
+
 Conda can help create a consistent environment.
 It can also be useful to install packages without root access.
 To use Conda, run:
@@ -196,6 +197,7 @@ mlcroissant validate --jsonld ../../datasets/titanic/metadata.json --debug
 ```
 
 This will:
+
 1. print extra information, like the generated nodes;
 2. save the generated structure graph to a folder indicated in the logs.
 
@@ -205,4 +207,3 @@ To publish a package,
 
 1. Bump the version in `croissant/python/mlcroissant/pyproject.toml`, and merge your PR.
 2. Publish a [new release](https://github.com/mlcommons/croissant/releases) in GitHub, and add a tag to it with the newest version in `pyproject.toml`. Ensure that the new release is marked as `latest`. The workflow script `python-publish.yml` will trigger and publish the package to [PyPI](https://pypi.org/project/mlcroissant/).
-

python/mlcroissant/mlcroissant/_src/core/dataclasses.py

@@ -5,9 +5,7 @@
 
 from __future__ import annotations
 
-from collections.abc import Iterator
-from collections.abc import Mapping
-from collections.abc import Sequence
+from collections.abc import Iterator, Mapping, Sequence
 import dataclasses
 import inspect
 from typing import Any, Callable, cast, Literal, TypedDict, Union