docs(home): drop "Vivliostyle.js and CLI" framing from Cookbook intro

The home-page Cookbook section was introduced as "Vivliostyle.js and
CLI の最近の追加機能" / "recent Vivliostyle.js and CLI features", but
the section actually covers cross-product material (core CSS, CLI,
VFM, themes), so naming only two of those products in the intro is
misleading.

- ja: "Vivliostyle.jsとCLIの最近の追加機能を実践的に解説:" →
        "最近追加された機能を、プロダクトを横断して実践的に解説:"
- en: "Practical guides to recent Vivliostyle.js and CLI features:" →
        "Practical, cross-product guides to recently added Vivliostyle features:"

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ogwata

content/en/index.md

@@ -38,7 +38,7 @@ Choose a product to get started:
 
 ## [Cookbook](/en/cookbook/)
 
-Practical guides to recent Vivliostyle.js and CLI features:
+Practical, cross-product guides to recently added Vivliostyle features:
 
 - [Footnotes](/en/cookbook/footnotes/) — DPUB-ARIA footnotes, the standard `@page { @footnote { } }` rule, and the new VFM `footnote` modes (v2.41.0+)
 - [CMYK Conversion](/en/cookbook/cmyk/) — `device-cmyk()` and CLI PDF CMYK output (v2.40.0+)

content/ja/index.md

@@ -38,7 +38,7 @@ Vivliostyleの最大のメリットは**SSMO（Single Source Multi Output）**
 
 ## [活用ガイド](/ja/cookbook/)
 
-Vivliostyle.jsとCLIの最近の追加機能を実践的に解説:
+最近追加された機能を、プロダクトを横断して実践的に解説:
 
 - [脚注（フットノート）](/ja/cookbook/footnotes/) — DPUB-ARIA脚注、標準 `@page { @footnote { } }` ルール、VFMの新しい `footnote` モード（v2.41.0+）
 - [CMYK 変換](/ja/cookbook/cmyk/) — `device-cmyk()` とCLIによるCMYK PDF出力（v2.40.0+）