fix: MD007/ul-indent: Unordered list indentation (EbookFoundation#7038)

[Expected: 4; Actual: 2]

(cherry picked from commit 2b71e73)

Author: davorpa

books/free-programming-books-cs.md

@@ -15,7 +15,7 @@
     * [Sítě](#site)
 * [LaTeX](#latex)
 * [Linux](#linux)
-  * [Distribuce](#distribuce)
+    * [Distribuce](#distribuce)
 * [OpenSource](#opensource)
 * [PHP](#php)
 * [Python](#python)