What this PR changes

In Workshop/workshop.md, the PDF 文稿 links for 第27期 and 第26期 rows were swapped:

• 第27期 row → pointed to 第26期Workshop/ directory
• 第26期 row → pointed to 第27期Workshop/ directory

Each period now links to its own directory, matching 第28期 ~ 第32期 rows which already did.

Why

A reader clicking 第27期's PDF 文稿 would land on 第26期's slides. Small factual link fix, no content change.

Scope

• 1 file: Workshop/workshop.md
• 2 link URL fixes (第27 ↔ 第26 directory refs), no body / semantic content change