DOC: Example applications in documentation

docs/appdev/examples/01_hello_cli.md

@@ -0,0 +1,52 @@
+<div align="center">
+  <h1>Example 01: Hello CLI</h1>
+  <p><em>The absolute basics. Writing a terminal program.</em></p>
+</div>
+
+---
+
+This example demonstrates the bare minimum structure of a BoredOS application that outputs text to the standard output (usually the Terminal executing the binary).
+
+## 📝 Concepts Introduced
+* Including `stdlib.h` for basic IO.
+* The `main()` entry point.
+* Using `printf()` for formatted output.
+
+---
+
+## 💻 The Code (`src/userland/cli/hello_world.c`)
+
+```c
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+    // Standard library initialization is handled automatically by crt0.asm
+    
+    // Print a simple string to the terminal
+    printf("Hello, World from BoredOS Userland!\n");
+    
+    // Print some formatted data
+    int favorite_number = 67;
+    printf("Did you know my favorite number is %d?\n", favorite_number);
+    
+    // Returning from main automatically terminates the process cleanly
+    return 0;
+}
+```
+
+## 🛠️ How it Works
+
+1.  **`#include <stdlib.h>`**: We include the SDK's standard library header which gives us access to `printf`.
+2.  **`int main(...)`**: Every process begins execution here (managed transparently by `crt0.asm`).
+3.  **`printf(...)`**: The SDK routes this call internally directly to the `SYS_WRITE` system call, making it available on the terminal.
+4.  **`return 0`**: A successful exit code. 
+
+## 🚀 Running It
+
+If you build the project, you can open the Terminal and type:
+```sh
+/ # hello_world
+Hello, World from BoredOS Userland!
+Did you know my favorite number is 67?
+/ # 
+```