Add Line Numbering Feature for Code Blocks

[martyanovandrey]

Enhance YFM by introducing a line numbering feature for code blocks. This feature would allow users to easily add line numbers to their code snippets, facilitating easier reference and discussion.

Proposed Solution

Introduce a new key, showLineNumbers, within the language meta string of code blocks.

Syntax Example

md input

```javascript showLineNumbers
const example = "This is a code block.";
console.log(examples);

result

1 const example = "This is a code block.";
2 console.log(examples);

"In the code block on line 2 ..."