docs: update code block filename in Module Aliases section (#66825)
The filenames of the last two code blocks on this page
https://nextjs.org/docs/app/building-your-application/configuring/absolute-imports-and-module-aliases#module-aliases
are written as comment instead of using the `filename` prop.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Co-authored-by: JJ Kasper <jj@jjsweb.site>