Fix article in description

src/index.pug

@@ -3,7 +3,8 @@
 - var isBehindBirthday =
 -   now.getUTCMonth() < 7 || (now.getUTCMonth() == 7 && now.getUTCDate() < 4)
 - var age = now.getUTCFullYear() - 2003 - (isBehindBirthday ? 1 : 0)
-- var about = `A ${age}-year-old human passionate about technology.`
+- var article = age == 18 ? `An` : `A`
+- var about = `${article} ${age}-year-old human passionate about technology.`
 
 doctype html
 html(lang="en")