markdown: fix redundant leading spaces in markdown list (#7178)
* fix rebundant leading spaces in markdown list
* add test for rebundant leading spaces in markdown_list
* add changelog_unreleased file of pr-7178
* Update changelog_unreleased/markdown/pr-7178.md
Co-Authored-By: Sosuke Suzuki <aosukeke@gmail.com>
* Update changelog_unreleased/markdown/pr-7178.md
Co-Authored-By: Sosuke Suzuki <aosukeke@gmail.com>
* fix minor issues
Co-authored-by: Sosuke Suzuki <aosukeke@gmail.com>
Co-authored-by: Georgii Dolzhykov <thorn.mailbox@gmail.com>