Many bug fixes and improvements (#1270)

* Add Ruby and Kotlin icons
Add the avatar of @curtishd

* Update README

* Synchronize zh-hant and zh versions.

* Translate the pythontutor blocks to traditional Chinese

* Fix en/mkdocs.yml

* Update the landing page of the en version.

* Fix the Dockerfile

* Refine the en landingpage

* Fix en landing page

* Reset the README.md

zh-hant/codes/java/chapter_sorting/radix_sort.java

@@ -50,12 +50,13 @@ public class radix_sort {
             if (num > m)
                 m = num;
         // 按照從低位到高位的順序走訪
-        for (int exp = 1; exp <= m; exp *= 10)
+        for (int exp = 1; exp <= m; exp *= 10) {
             // 對陣列元素的第 k 位執行計數排序
             // k = 1 -> exp = 1
             // k = 2 -> exp = 10
             // 即 exp = 10^(k-1)
             countingSortDigit(nums, exp);
+        }
     }
 
     public static void main(String[] args) {