fix highlighted change to header.js snippet (#23985)
fix highlighted change to header.js snippet (#23985)

* fix highlighted change to header.js snippet

* highlight with JS comments instead of JSX comments

* remove the old JSX highlight comments

whoops, editing code directly within GitHub.com is weird 😅

* chore: format

Co-authored-by: gatsbybot <313a651c59fdaade90d152972001707d94b0975c@gmail.com>
gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby