Refact: Updated rootAsHeadingTip (#14363)

### What problem does this PR solve?

Updated rootASHeadingTip.

### Type of change

- [x] Documentation Update

web/src/locales/en.ts

@@ -1513,9 +1513,9 @@ Example: Virtual Hosted Style`,
       includeHeadingContent: 'Include heading content',
       includeHeadingContentTip:
         'When enabled, content directly under a heading is kept as its own chunk. Child chunks keep only the heading path.',
-      rootAsHeading: 'Use root as H0 heading',
+      rootAsHeading: 'Set first chunk as global context',
       rootAsHeadingTip:
-        'Treat the root node as a H0 heading when building the hierarchy',
+        'Treats the initial split as a global heading to maintain consistent context across the document hierarchy. Ideal for resumes where the first section identifies the subject.',
       hierarchyTip: `Build a heading tree and produce self-contained chunks, each carrying its full ancestor heading path (e.g. Part 1 › Chapter 3 › Section 2 + body text).\n
 Best for: Documents with independent, structurally significant sections — such as legal statutes, regulations, contracts, and technical specifications — where each chunk must be identifiable by its structural position even without surrounding context.`,
       groupTip: `Split the document flat at a chosen heading level and automatically merge adjacent small sections to preserve content continuity. No parent-heading path is injected.\n

web/src/locales/zh.ts

@@ -1264,6 +1264,8 @@ General：实体和关系提取提示来自 GitHub - microsoft/graphrag：基于
       includeHeadingContent: '包含标题内容',
       includeHeadingContentTip:
         '启用后，标题下的直接内容将作为一个独立的块保留。子块仅保留标题路径。',
+      rootAsHeading: '将首个切片设为 H0 标题',
+      rootAsHeadingTip: '将首个切片设为全局标题，以确保整个文档层级结构中拥有一致的上下文信息。该功能尤其适用于首段包含关键信息的简历。',
       hierarchyTip: `构建标题树并生成独立的块，每个块携带其完整的祖先标题路径（例如 第1部分 › 第3章 › 第2节 + 正文）。\n
 适用场景：具有独立的、结构性重要章节的文档——如法律条款、法规、合同和技术规范——其中每个块即使没有上下文也能通过其结构位置来识别。`,
       groupTip: `在选定的标题级别将文档扁平分割，并自动合并相邻的小节以保持内容连续性。不注入父标题路径。\n