Add guides on Getting Started with JS (#4150)

- Get started section added to the JS docs
- Small fixes in the JS modules docs

documentation/js/js_using_js_modules.md

@@ -0,0 +1,42 @@
+# Using JavaScript modules {#js_using_js_modules}
+
+In the previous guides, we learned how to write a basic JavaScript app using [built-in functions](#js_builtin). However, the set of built-in functions is limited, so when developing your JS apps, you'll likely want to use external JS modules. These modules offer a wide range of functions (methods) for various tasks.
+
+For example:
+* The `serial` module enables transmitting and receiving data via a serial interface
+* The `badusb` module enables USB keyboard emulation and sending key press events via USB
+* The `math` module provides mathematical functions
+
+JS modules are written in C/C++, making them fast and efficient. They come with Flipper Zero firmware and are stored on the microSD card in compiled form as **FAL (Flipper Application File)** files.
+
+> [!note]
+> You can find the implementation of all supported JS modules in the [Flipper Zero firmware repository](https://github.com/flipperdevices/flipperzero-firmware/tree/dev/applications/system/js_app/modules). Also, check out the [docs for JS modules](#js_modules) for more details.
+
+## How to use JS modules in your app
+
+Before using any of the JS module methods, you **must** import the module using the `require()` function. This loads the module into RAM, allowing you to access its methods.
+
+To save RAM and improve performance, avoid loading modules you don't plan to use. Also, all loaded modules will be automatically unloaded from RAM after the app execution ends.
+
+To load a module, call the `require()` function with the module name in quotes. For example, to load the `notification` module, write this:
+
+\code{.js}
+let notify = require("notification");
+\endcode
+
+Now you can call methods of the `notification` module using the `notify` variable to access them:
+
+\code{.js}
+let notify = require("notification");
+
+notify.success();
+print("success notification");
+\endcode
+
+## What's next?
+
+Congratulations, you've completed the **Getting Started** section of our JS docs. You've learned how to run and debug JS apps, and how to use JS modules. Now, we invite you to check out the [main JavaScript page](#js) where you'll find:
+
+* JavaScript app examples
+* Documentation on JS modules
+* Additional resources related to JavaScript on Flipper Zero