Markdown Style & Linting Fixes?

[kraker]

@livialima Would you be interested in stylistic edits and linting of the markdown files in this repository?

For example, setting an 80 character width limit would help with readability of the raw markdown text and using fenced code blocks instead of indented blocks would allow us to utilize syntax highlighting.

These are a couple of things that jumped out at me when working with the project. Running the code-base through a markdown linter might catch most of it.

If you're open to it, I would get started working on a PR for this.

[livialima]

Yes, please! Any help in the readability of the lessons is very welcomed.