* dvc: fixes dvc.scm.Git.get_diff_trees docstring imprecision.
Parentheses were used in the "Returns:" description but its a dict, so changed to curly brackets;
and specified the 2 possible forms of the return structure.
* dvc: updates zsh autocomplete script with current command help messages.
Comparing vs actually running each command's `-h` help output.
* dvc: begins updating bask autocomplete script...
Only reorders existing commands and adds comments for those missing.
* scripts: removes temporary comments in bash autocomplete script.
Per https://github.com/iterative/dvc/pull/2064#pullrequestreview-243578115
Related to #2069
Naba7
Jorge Orpinel
Mr. Outis