Several improvements (#1002)

* Update buttons.

* Update button svg

* Update button

* Update README.md

* Update index.md

* Update translation of about_the _book

* Update English headings.

README.md

@@ -11,11 +11,11 @@
 
 <p align="center">
   <a href="https://www.hello-algo.com/">
-    <img src="https://www.hello-algo.com/index.assets/btn_read_online_dark.svg" width="155"></a>
+    <img src="https://www.hello-algo.com/index.assets/btn_read_online_dark.svg" width="145"></a>
   <a href="https://github.com/krahets/hello-algo/releases">
-    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_dark.svg" width="155"></a>
+    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_dark.svg" width="145"></a>
   <a href="https://github.com/krahets/hello-algo/blob/master/README-en.md">
-    <img src="https://www.hello-algo.com/index.assets/btn_english_edition_dark.svg" width="155"></a>
+    <img src="https://www.hello-algo.com/index.assets/btn_english_edition_dark.svg" width="145"></a>
 </p>
 
 <p align="center">

codes/c/chapter_array_and_linkedlist/linked_list.c

@@ -28,9 +28,10 @@ void removeItem(ListNode *n0) {
 
 /* 访问链表中索引为 index 的节点 */
 ListNode *access(ListNode *head, int index) {
-    while (head && head->next && index) {
+    for (int i = 0; i < index; i++) {
+        if (head == NULL)
+            return NULL;
         head = head->next;
-        index--;
     }
     return head;
 }

docs-en/chapter_preface/about_the_book.md

@@ -40,6 +40,6 @@ During the creation of this book, I received help from many people, including bu
 
 During the writing process, I read many textbooks and articles on data structures and algorithms. These works provide excellent models for this book and ensure the accuracy and quality of its contents. I would like to thank all my teachers and predecessors for their outstanding contributions!
 
-This book promotes a hands-on approach to learning, and in this respect is heavily inspired by ["Hands-On Learning for Depth"](https://github.com/d2l-ai/d2l-zh). I highly recommend this excellent book to all readers.
+This book promotes a hands-on approach to learning, and in this respect is heavily inspired by ["Dive into Deep Learning"](https://github.com/d2l-ai/d2l-zh). I highly recommend this excellent book to you.
 
-A heartfelt thank you to my parents, it is your constant support and encouragement that gives me the opportunity to do this fun-filled thing.
+**A heartfelt thank you to my parents, it is your constant support and encouragement that gives me the opportunity to do this fun-filled thing**.