added support for multilingual 404 page redirects

exampleSite/config/development/server.toml

@@ -0,0 +1,13 @@
+# defaultContentLanguageInSubdir must be true for this to work.
+
+# Other languages redirects
+# [[redirects]]
+# from = '/fr/**'
+# to = '/fr/404.html'
+# status = 404
+
+# Default language must be last.
+[[redirects]]
+from = '/**'
+to = '/en/404.html'
+status = 404

exampleSite/hugo.toml

@@ -17,7 +17,7 @@ disableLanguages = [
 hasCJKLanguage = false #  If hasCJKLanguage true, auto-detect Chinese/Japanese/Korean Languages in the content. see: https://gohugo.io/getting-started/configuration/#hascjklanguage
 # default language
 defaultContentLanguage = 'en'
-defaultContentLanguageInSubdir = false
+defaultContentLanguageInSubdir = true
 
 ########################### Services #############################
 [services]