Fixed small running on YARN docs typo

The backslash is needed for multiline command

Author: Vlad <frolvlad@gmail.com>

Closes #1158 from frol/patch-1 and squashes the following commits:

e258044 [Vlad] Fixed small running on YARN docs typo

(cherry picked from commit b88238faeed8ba723986cf78d64f84965facb236)
Signed-off-by: Thomas Graves <tgraves@apache.org>