[WIP] make .editorconfig easier to share the setting

[NguyenTrung1995]

To do

• Auto provide .editorconfig file when the project not contain it. ✅
• If the project contain .editorconfig file, we will add rules that it does not.

[TakuyaAbe]

@NguyenTrung1995

Please add the editor config into https://github.com/fourdigit/editorconfig-config-fourdigit , not do work on this repository.

If the project contain .editorconfig file, we will add rules that it does not. I think this behavior is may not good.

Let me explain with a example.

Alice: Developer 1(who make repo & config file of editoconfig) Bob: Developer 2(who clone the repository that Alice made)

1. Alice create a project (without .editorconfig)
2. Alice add editorconfig by running yarn add @fourdigit/eslint-config-fourdigit
3. Alice do git commit & git push
4. Alice modify editor config & git push
5. Bob clone the repository
6. postinstall of eslint-config-fourdigit run automatically & editorconfig is modified by the script
7. Bob have to reset the modification by the postinstall because the genue setting of the project is what Alice modified.

Everytime other developer joins, the burden occurs. So, the strategy "If the project contain .editorconfig file, we will add rules that it does not." might not better.

Instead of adding the feature, please add a instruction to update editorconfig. e.g.

## Update .editorconfig

When this package is installed & no `.editorconfig` file is existed on your project, npm automatically copies the config from `ndoe_modules/@fourdigit/editorconfig-config-fourdigit/.editorconfig` to project root.
When you want to update your editorconfig manually, please run following command.  

cp './node_modules/@fourdigit/editorconfig-config-fourdigit/.editorconfig' .editorconfig

[TakuyaAbe]

https://www.npmjs.com/package/@fourdigit/editorconfig-config-fourdigit で公開済み