typo on customize themes page

[verhulstm]

the page

https://www.nebari.dev/docs/explanations/customize-themes

has a non-functional example config

the yaml has a few issues -- mostly just formatting

including "narbar_hover_color: "#00a3b0"," -- with an "r"

[marcelovilla]

Thanks @verhulstm! I've opened nebari-dev/nebari-docs#564. Feel free to open a PR to fix the typo if you have the time!