chore: add docs and example

example/01_simple_struct/main.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include "cmeta.h"
+
+typedef struct {
+    int int_field;
+} Foo_Struct;
+
+int main(void) {
+    printf("Foo_Struct infos:\n");
+    printf("  name = %s\n", foo_struct_info.name);
+    printf("  fields_count = %zu\n", foo_struct_info.fields_count);
+
+    for (size_t i = 0; i < foo_struct_info.fields_count; i += 1) {
+        Field_Info field = foo_struct_info.fields[i];
+        printf("    .%s: %s\n", field.name, field.type);
+    }
+
+    return 0;
+}