Keep Italian documentation behind an English-first navigation disclosure

Author: Mattboxx

README.md

@@ -12,9 +12,15 @@ module, and a later `begin()` starts it again.
 FindMyAdv is an unofficial, open-source interoperability project. It is not
 affiliated with or endorsed by Apple, Google, or Espressif.
 
-Italian documentation: [`docs/README.it.md`](docs/README.it.md)  
 Complete API reference: [`docs/API.md`](docs/API.md)
 
+<details>
+<summary>Italian documentation</summary>
+
+[`Guida italiana`](docs/README.it.md). English is the primary documentation language.
+
+</details>
+
 Additional references:
 
 - [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md)