chore(maintenance): add markdownlint

[dreamorosi]

Description of your changes

This PR introduces markdown linting to the project. This will enforce an objective baseline for style and format of markdown files.

To support this I have added markdownlint-cli2 to the workspace, this is the same CLI used by Powertools for AWS Lambda (Python) from which I also copied the rule set.

Linting is run automatically as pre-commit hook via lint-staged, which will lint and fix only on staged files that are about to be committed (remember to run npx husky to make it take effect), and also as PR check. The latter runs on all markdown files in scope.

The tool supports an ignore file, which I also added to the project, however I was able to make this file work only with the IDE extension but not the CLI, for this reason I replicated the patterns in the command I added to the package.json.

For the time being I have ignored the package/*/README.md files since there are opened issues already for these, once we tackle them we will remove them from the ignore list.

Finally, if you are using VSCode, I recommend to install the markdownlint which will surface the issues according to the ruleset defined and can also be configured to format on save.

Related issues, RFCs

Issue number: #2399

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective and works
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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[am29d]

Great addition! I tested few formatting errors and the error messages are spot on what's wrong, where and what to fix ✅.

Just two comments on the configuration, it seems like they are not valid based on the JSON schema of markdownlint? Maybe I am missing something.

[dreamorosi]

No, you're right - I copied the config from the Python repo assuming it was correct but the two settings you pointed out are either missing or have been removed, they don't appear anymore in the docs for the tool either.

I have removed them both!

I also opened an issue in aws-powertools/powertools-lambda-python#4208

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud