[Feature Request] - Make theme selection automatic in GitHub Markdown

@lunatic-fox is already working on this.

Since Oct 28, 2022.

### Original issue

- [X] Confirm

### API parameter

theme

### Problem to be solved

`theme` parameter only provides a standard color to the icon: `#ffffff` *(dark theme)* or `#000000` *(light theme)*. But it does not automatically select which theme should be used depending on GitHub Markdown theme.

### Possible solution

## Solution #​1 - `currently implemented`
 I recently created a interface page to make easier to use GitHub Markdown logic wrapping the themed icons. The generated code will be like the example below.

***Example using `html5` icon***
```html

```

## Solution #​2 - `work with adjustments`
> Suggested by: @Snailedlt

 We can use `#gh-dark-mode-only` and `#gh-light-mode-only` suffixes, but, as far as I searched, they only work to actual images. Which means the icons must be on an endpoint.

***Example using `javascript` icon***
```markdown
```
 As it does not work with API query, it's possible to create those endpoints by adding a new "generator program" *(@develop/generator/generators)* to build them.
With this solution they will work like `./icons` endpoints of Devicon repository.

## Solution #​3 - `does not work properly`
 The best solution would be to use the API to return a `.svg` with some logic to automatically choose the correct theme. That way we could make just one request.

***Example using `css3` icon***
```markdown
```
 This was tested and does not work with GitHub theme, only with browser theme.

### Additional information

I'm searching some ways to implement the solution #​3 or something close to it. If you have any ideas, it would be great to read them here.

This issue closes NONE