* A few spelling and grammer fixes on readme
Changes a few wording, some punctuation and grammar.
* Grammar and punctuation on Roadmap
Mostly grammar and punctuation on the roadmap
* Update README.md
Restore British English spelling of favourite, because it's used on the API endpoints in Roadmap as well.
* Grammar and punctuation on Contributing
Mainly grammar and punctuation on Contributing file.
* add note about alpha + beta, link to roadmap
* rename progress => roadmap
* edit / update roadmap
* add note that 2023 date is only an estimate
* clarify that order of features may change
* add 'best-guess' note at the top
Martijn de Boer