diff --git a/docs/translations.md b/docs/translations.md
new file mode 100644
index 00000000..689bf8c0
--- /dev/null
+++ b/docs/translations.md
@@ -0,0 +1,20 @@
+# Modify an existing language
+
+Go to `_locales` folder, select the language and edit the `.json` files.
+
+# Add a new language
+
+1. Edit `package.json / babel / plugins / "i18next-extract" / locales` to
+   include the new language tag.
+2. Edit
+   `src / js / page / loader.mjs / function initTranslations / supportedLngs` to
+   include the new language tag.
+3. Run `npm install` (If the project is already installed, skip this step.)
+4. Run `npm run dev:rollup`
+5. Edit `_locales / <NEW LANGUAGE TAG> / *.json` files
+
+\*\* You can use https://r12a.github.io/app-subtags/ to `check` if the new
+language tag is valid.
+
+**IMPORTANT:** Hyphen-separated tags must use 'underscore' (ex. en-US --must
+be--> en_US).
diff --git a/package.json b/package.json
index 52116b0a..10578552 100644
--- a/package.json
+++ b/package.json
@@ -4,8 +4,8 @@
     "prepare": "husky install",
     "release": "node scripts/release.mjs",
     "clean": "rm -rf ./dist",
-    "dev:babel": "export ODOO_TERMINAL_ENV=development && babel --quiet 'src/**/*.{js,mjs}'",
-    "dev:watch": "export ODOO_TERMINAL_ENV=development && rollup -c -w",
+    "dev:rollup": "export ODOO_TERMINAL_ENV=development && rollup -c",
+    "dev:rollup:watch": "export ODOO_TERMINAL_ENV=development && rollup -c -w",
     "dev:tests": "export ODOO_TERMINAL_ENV=development && node scripts/build.mjs && poetry run pytest",
     "prod:build": "export ODOO_TERMINAL_ENV=production && node scripts/build.mjs",
     "start:firefox": "export ODOO_TERMINAL_ENV=development && node scripts/build.mjs && web-ext run --verbose -t firefox-desktop",