Using British and American english in code and documentation

The vf-core project is being led by EMBL where British English is used, we're also aware that most code is American English (colour vs color); so:

• 📚🇬🇧 Documentation is written in British English 💂‍ Rarely use centred text, always use colours
• ⌨️🇺🇸 Code is written in American english 🧢 $vf-main-color: green;