Add note on how to add a new translation key (#2536)

* Add note on how to add a new translation key

* Lint

* Nit

README.md

@@ -141,6 +141,28 @@ Run backend components:
 yarn backend
 ```
 
+### Add a new translation key
+
+To add a new translation key you can do these steps:
+
+1. Add the new key entry to the code where the new key is used: `t("some_new_key")`
+1. Run `yarn i18n` to extract the new key and update the translation files. This will add a skeleton entry to the `public/locales/en-GB/app.json` file:
+   ```jsonc
+   {
+       ...
+       "some_new_key": "",
+       ...
+   }
+   ```
+1. Update the skeleton entry in the `public/locales/en-GB/app.json` file with the English translation:
+   ```jsonc
+   {
+       ...
+       "some_new_key": "Some new key",
+       ...
+   }
+   ```
+
 ## Documentation
 
 Usage and other technical details about the project can be found here: