Add "examples/snprintf[_va].c"

examples/snprintf.c

@@ -0,0 +1,22 @@
+#include <kernaux/printf.h>
+
+#include <assert.h>
+#include <string.h>
+
+#define BUFFER_SIZE 1024
+
+static char buffer[BUFFER_SIZE];
+
+int main()
+{
+    const int result = kernaux_snprintf(
+        buffer,
+        sizeof(buffer),
+        "Hello, %s! Session ID: %u.",
+        "Alex",
+        123
+    );
+    assert((size_t)result == strlen(buffer));
+    assert(strcmp(buffer, "Hello, Alex! Session ID: 123.") == 0);
+    return 0;
+}