BulmaJS is still in development, you can keep track of current, pending, completed and planned tasks on the official Trello board.
tl;dr GIMME THE DOCS! Well here you go.
If you would like to contribute a plugin, fix a bug or fix some horrible typo in the docs, then please submit a PR if you can! Alternatively, create an issue. Please note, while the code base doesn't follow any strict style, try to ensure your PRs follow the general convention that you see. There may be times the convention isn't followed, so if you see this submit an issue/PR and slap me on the wrist :). Any PR/issue at this time will not be rejected but may have some alteration to the code.
If you are submitting a plugin, please also submit the relevant documentation.