Markdownlint compatible

[VikashKothary]

Hey, love what you've done here. It looks super cool and useful.

I'm currently using this markdownlint pre-commit to check all my files:

-   repo: git://github.com/igorshubovych/markdownlint-cli
    rev: v0.5.0
    hooks:
    -   id: markdownlint

And I get these errors when linting the markdown generated by this pre-commit.

README.md: 7: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 1]
README.md: 15: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 7]
README.md: 16: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 7]
README.md: 18: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 6]
README.md: 19: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 8]
README.md: 20: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 1]
README.md: 6: MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [Context: "```"]
README.md: 21: MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [Context: "```"]
README.md: 6: MD040/fenced-code-language Fenced code blocks should have a language specified [Context: "```"]

To fix this, I think three things needed to be added to the generated makefile-doc:

1. Trim all training spaces
2. Add spaces before and after the ```
3. Add a language to the ```

I think having this compatible with markdownlint would be a nice feature.

[mbideau]

Hi,
First thank you for your code. It works great.

I am having the same issue as @VikashKothary.

I would be glad to see the work from @johncblandii in its fork https://github.com/johncblandii/pre-commit-makefile merged into this project.

Also my suggestion to extend @johncblandii work would be to remove the inserted line $ make help and replace the fenced code block language by text instead of bash.

[mbideau]

Actually, I did a fork of @johncblandii and implemented what I have said.
It is available here : https://github.com/mbideau/pre-commit-makefile/releases/tag/v0.3.0.
It generate valid markdown output now.
Feel free to copy/retrieve my commits.

[johncblandii]

Glad it helped, @mbideau.