Navigate to src/datas and open defaults.json.
In defaults.json, add in the language code with corresponding flag and language name in that language. Please reference this for language code.
Navigate to src/datas/markdowns and create a folder with your language code as the name of the folder.
Now, inside that folder, add the files with the same name in the same nested folder structure as in en folder.
In each files and sub-files in src/components, see if i18n element tag is already there. If so, add a new language with using your language code following the same key and syntax as in English separated by comma.