✨Support spell checking in editor

## Description
Previously, we had to turn off `spellcheck` in the editor because it would not help fix the typo; it would just underline the misspelled words. 
Based on @lostdesign suggestion, I think it would be a good idea to implement `spellcheck` feature using [`wooorm/dictionaries`](https://github.com/wooorm/dictionaries) and `nspell`. 