Indent all lines that begin in the region, moving the affected lines
as a rigid unit (@code{indent-rigidly}).
-If called with no argument, the command activates a transient mode for
+If called with no argument, this command activates a transient mode for
adjusting the indentation of the affected lines interactively. While
this transient mode is active, typing @kbd{@key{LEFT}} or
@kbd{@key{RIGHT}} indents leftward and rightward, respectively, by one