Add text to <insert> mode info noting that Escape Chars may have led there.

[ethanmsl]

Current text only mentions that pressing escape can lead you there.
But a reasonable source of confusion would be entering escape chars via some key combinations (e.g. Alt+_).

This is 'simply' done via customization of the starship.toml file. Though there may be some nuance in not over-elaborating the message there.