Fix docstring of project.Project.PrintWorkTreeStatus()

Change-Id: I1a9139d2ea3b3331a6f3ad3cae9e0ac37074d716
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/251837
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Rostislav Krasny <rostigm@gmail.com>

project.py

@@ -1065,7 +1065,7 @@ class Project(object):
     """Prints the status of the repository to stdout.
 
     Args:
-      output: If specified, redirect the output to this object.
+      output_redir: If specified, redirect the output to this object.
       quiet:  If True then only print the project name.  Do not print
               the modified files, branch name, etc.
     """