feat: `tldr`

[prdrj]

When user triggers tldr with a command, the bot should reply with an embed with the tldr of the corresponding command.

tldr-pages are written in simple markdown so, all the pages can be possibly cached and parsed.

Example usage:

$tldr rm

Bot Reply:

  rm

  Remove files or directories.
  See also: rmdir, trash.
  More information: https://www.gnu.org/software/coreutils/manual/html_node/rm-invocation.html.

  Remove specific files:

    rm path/to/file1 path/to/file2 ...

  Remove specific files ignoring nonexistent ones:

    rm --force path/to/file1 path/to/file2 ...

  Remove specific files interactively prompting before each removal:

    rm --interactive path/to/file1 path/to/file2 ...

  Remove specific files printing info about each removal:

    rm --verbose path/to/file1 path/to/file2 ...

  Remove specific files and directories recursively:

    rm --recursive path/to/file_or_directory1 path/to/file_or_directory2 ...

  Remove empty directories (this is considered the safe method):

    rm --dir path/to/directory