fix: rename 404 text

[norrec99]

#42 (comment)
I used capital letters for the replacement of "404" text

Here how it looks

And this is the lower case "Error" message

I think the first one looks better but I can change according to your liking

[ryancwalsh]

@norrec99 Of those 2, I prefer the second one ("Error"). But I'd also be curious to see a version where you remove "Error" (and the gray vertical line) entirely.

[norrec99]

It looks like that:

[ryancwalsh]

@norrec99 Cool, I like that version (#45 (comment)) the best.