Improve README formatting

[Dippp10]

Minor README improvement

[github-actions]

Linter failed, fix the error(s):

free-programming-books/books/free-programming-books-lg.md
13:1-13:133  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
14:1-14:120  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
20:1-20:143  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
26:1-26:117  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
27:1-27:101  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
33:1-33:116  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 39:1-39:99  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 45:1-48:47  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 46:3-46:53  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
47:3-47:104  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 48:3-48:47  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 49:1-49:85  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 50:1-50:77  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
55:3-55:102  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint
 56:3-56:34  warning  Marker style should be `*`  unordered-list-marker-style  remark-lint