Fix formatting of Docker 20.10 release note

[tnir]

Fixes #660.

• Unifies bullet marker */+/- with * mainly to remove the extra margin between items (see the screenshot below).
• Applies \`` to the commands and arguments of the command.

Screenshots

Before	After
https://github.com/docker/docker-ce/blob/002bd8bf4608d068ff83167df34dcdbd55e61892/CHANGELOG.md	https://github.com/docker/docker-ce/blob/5989c651d2e563a6ee1a99f638e04b7cced86431/CHANGELOG.md

Note: * vs + vs -

$ cut -c 1 CHANGELOG.md | sort | uniq -c
     24
      8
     13 #
     62 *
     26 +
     25 -
      1 F
      1 [

[tnir]

@tiborvass Could you help me how to generate the original changelog in #660?

[tiborvass]

Thanks, modified it to do - instead.