Update README.md

[Sallaa]

• README.md is not up to date anymore and doesn't reflect the status of the repository.

Some proposed enhancements:

• [x] Explain which version of the translation to use
• [x] Remove Firefox
• [x] Fix typos
• [x] How do I add an item to the Navbar of this project -> Update when the navbar is refactored
• [x] Remove the examples for "How do I add a tool to this project"
• [ ] Add a collaboration section / collaboration guidelines
• [x] Remove the redux examples, we will update Redux in the same release
• [x] Add License

[Sallaa]

I believe we should not add the How do I add an item to the Navbar of this project section anymore. The code should be self explanatory once the refactoring is done and the code is polished.