fix: #133 update LOCALE config to cover overall locales

Update LOCALE inside config.ts to include html lang value and datetime locale values. Updated respective files and blog post.

Closes: #133

src/config.ts

@@ -10,7 +10,10 @@ export const SITE: Site = {
   postPerPage: 3,
 };
 
-export const LOCALE = ["en-EN"]; // set to [] to use the environment default
+export const LOCALE = {
+  lang: "en", // html lang code. Set this empty and default will be "en"
+  langTag: ["en-EN"], // BCP 47 Language Tags. Set this empty [] to use the environment default
+} as const;
 
 export const LOGO_IMAGE = {
   enable: false,