ultra-short, illustrative story for patterns

Story provides a more narrative, less academic description to a pattern. When a pattern has a good narrative description at the first few sections, it helps people deciding quickly whether this is something they want to dive deeper. Some patterns provide good narrative while some other patterns lack those narrative angle. It would help to add story or improve narrative description to the patterns that don't have good narratives.

Issue 中沒有指定檔案或測試。檢查 repository 的 pattern 文件，並找出開頭部分缺少簡潔敘述的項目；當所選的 pattern 具有有用的故事，能幫助讀者決定是否進一步探索時，即表示完成。