Add reproduction steps for firefox to README

[PatrykKuniczak]

Is your feature request related to a problem? Please describe.
README.md don't have reproduction steps to load plugin in firefox.

Describe the solution you'd like
Add new things, and simplyfy a little:

### Procedures <a name="procedures"></a>

1. Clone this repository.
2. Change `name` and `description` in package.json => **Auto synchronize with manifest** 
3. Run `yarn install` or `npm i` (check your node version >= 16.6, recommended >= 18)

## And next, depending on the needs:

### For Chrome:
   1. Run `yarn dev` or `npm run dev`
   2. Open in browser - `chrome://extensions`
   3. Check - `Developer mode`
   4. Find and Click - `Load unpacked extension`
   5. Select - `dist` folder (after dev or build)

#### If you want to build for production, Just run `yarn build` or `npm run build`.

### For Firefox:
   1. Run `yarn dev:firefox` or `npm run dev:firefox`
   2. Open in browser - `about:debugging#/runtime/this-firefox`
   3. Find and Click - `Load Temporary Add-on...`
   4. Select - `manifest.json` file from `dist` folder (after dev or build)

#### If you want to build for production, Just run `yarn build:firefox` or `npm run build:firefox`.

#### Remember in firefox you add plugin in temporary mode, that's mean is disappear after close browser, you must do it again, on next launch.

[Jonghakseo]

Great, create a pull request and I'll incorporate it.

[Jonghakseo]

@all-contributors please add @PatrykKuniczak for docs

[allcontributors]

@Jonghakseo

I've put up a pull request to add @PatrykKuniczak! 🎉