Add Markdown Emoji on : (colon)

Would be a cool feature to preview emojis when you type the colon : key.

I know in windows you can use Win + . to preview an emoji box, but sometimes you might be using Hashnode on mobile or other devices that don't support emojis. plus, new users that are familiar with platforms like GitHub, Slack, or Discord will probably try to use emojis this way by default. :smile :smile :smile