I've had to manually add more colors to the plugin for general use cases. However I thought that this might be a feature that could be added. I've currently added the following colors to the plugin:

Black
Dark Grey
Dark Red
Dark Orange
Dark Yellow
Dark Green
Dark Blue
Dark Purple

All these colors are for the banner color. I don't believe at this time that any colors should be added to the text color list.

Feel free to share your RGB strings and I might consider adding those :) 

Sure! I've created a table on Google Sheets. You can refer to it here: https://docs.google.com/spreadsheets/d/1KcT0fyRnwpfXFBO1jtEiyr5BttNo20YdsslA8PI5BwI/edit?usp=sharing

Nice one thanks!

No problem! :D Thanks for the quick replies! Cant wait for the update!