refactor: reword locale translations (#12118)

### What problem does this PR solve?

Reword (in locales/en) "Image context window" to "Image & table context
window", etc.

### Type of change

- [x] Refactoring

web/src/locales/zh.ts

@@ -1813,6 +1813,7 @@ Tokenizer 会根据所选方式将内容存储为对应的数据结构。`,
       keywords: '关键词',
       questions: '问题',
       metadata: '元数据',
+      toc: '目录',
       fieldName: '结果目的地',
       prompts: {
         system: {