fix: typescript definitions for t function without namespaces

[pedrodurek]

Fix bugs: #1213 and #1212

In addition, I also added two examples of use and included the reference in the README file. Moreover, now that prettier is supporting typescript 4.1 (prettier/prettier#9234) I also bumped the prettier version and run it on type definitions file.

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test
• tests are included
• documentation is changed or added

[coveralls]

Coverage remained the same at 95.692% when pulling ab25221 on pedrodurek:master into a4aaf65 on i18next:master.

[Thanaen]

Hi !
I've tried to apply the new TS 4.1 example, but it seems to break when a there is a key named "keys" in the translations file :-(
Here is a simple repo I used to reproduce this issue. Simply clone it, do 'yarn' then 'yarn lint' / 'yarn start' !
Here is the repository: https://github.com/Thanaen/repro-react-i18n-ts-bug

[jamuhl]

@Thanaen this looks like a different issue?!? My suggestion would be creating a new issue for that and mentioning @pedrodurek

[Thanaen]

@jamuhl Okay, creating a new issue ! Thanks for your suggestion 👍

[jamuhl]

was published in react-i18next@11.8.1