git-changelog:tldr:a4a3d
This command is not a standard Git command. However, it appears to be a custom command or script that generates a changelog between two git tags, 2-1-0 and an unspecified previous tag.
The --list option suggests that the command will list the changes in a readable format rather than applying any modifications to the repository.
The --start-tag option is used to specify the starting tag from which the changelog will be generated. In this case, it is set to ${2-1-0}, which indicates that the tag value should be taken from the second argument passed to the command. If the second argument is not provided or is empty, the default value 1-0-0 will be used.
In summary, this command is likely a customized script that generates a changelog listing the changes between the specified tag 2-1-0 and an optional previous tag.