Revisit the English version (#1885)

* Update giscus scroller.

* Refine English docs and landing page

* Sync the headings.

* Update landing pages.

* Update the avatar

* Update Acknowledgements

* Update landing pages.

* Update contributors.

* Update

* Fix the formula formatting.

* Fix the glossary.

* Chapter 6. Hashing

* Remove Chinese chars.

* Fix headings.

* Update giscus themes.

* fallback to default giscus theme to solve 429 many requests error.

* Add borders for callouts.

* docs: sync character encoding translations

* Update landing page media layout and i18n

ja/docs/index.html

@@ -105,18 +105,6 @@
             <!-- mac height = 248.1 mm -->
             <!-- ipad height = 280.6mm -->
             <!-- iphone height = 160.7mm -->
-            <div class="media-block">
-                <a href="chapter_paperbook/">
-                    <div style="height: 8.17%;"></div>
-                    <img class="device-on-hover" style="height: 66.83%;" src="../assets/hero/cover_render.png" alt="Cover">
-                    <div class="text-button">
-                        <span>紙書籍を入手</span>
-                        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512">
-                            <path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z" />
-                        </svg>
-                    </div>
-                </a>
-            </div>
             <div class="media-block">
                 <a href="chapter_hello_algo/">
                     <div style="height: 4.34%;"></div>
@@ -265,7 +253,7 @@
 
         <!-- code reviewers -->
         <div style="margin: 2em auto;">
-            <h3>コード翻訳者</h3>
+            <h3>コードレビュアー</h3>
             <p>本書の多言語コード版は、以下の開発者の協力によって実現しました。ご尽力に感謝します！</p>
             <div class="profile-div">
                 <div class="profile-cell">