Add comment in component_with_printf example

Author: catamorphism

component-model/examples/tutorial/c/adder/component_with_printf.c

@@ -4,6 +4,12 @@
 uint32_t exports_docs_adder_add_add(uint32_t x, uint32_t y)
 {
 	uint32_t result = x + y;
+        // On traditional platforms, printf() prints to stdout, but on Wasm platforms,
+        // stdout and the idea of printing to an output stream is
+        // introduced and managed by WASI.
+        //
+        // When building this code with wasi-libc (as a part of wasi-sdk), the printf call
+        // below is implemented with code that uses `wasi:cli/stdout` and `wasi:io/streams`.
 	printf("%d", result);
 	return result;
 }