See "Reset, restore and revert" in linkgit:git[1] for the differences
between the three commands.
+THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
+
OPTIONS
-------
-s <tree>::
commit, branch or tag associated with it.
+
If not specified, the default restore source for the working tree is
-the index, and the default restore source for the index index is
+the index, and the default restore source for the index is
`HEAD`. When both `--staged` and `--worktree` are specified,
`--source` must also be specified.