[FEATURE] Ignore the LeetCode directory when building `DIRECTORY.md`

[Panquesito7]

Detailed description

The LeetCode folder should be ignored while building the DIRECTORY.md file.
There's already a DIRECTORY.md file for the LeetCode directory. We do not want duplicates.

Context

This would reduce the length of the root DIRECTORY.md file and keep things clean, as there's already a directory file in the LeetCode directory (as I explained above).

Possible implementation

Exclude the LeetCode directory while building the DIRECTORY.md file.

Additional information

Working on this.