[LyX/master] Yet another ru update by Yuriy

[Juergen Spitzmueller]

commit 7860d19fbc7472ba4e3c86b5dc495ea115d701e7
Author: Juergen Spitzmueller <spitz at lyx.org>
Date:   Mon Jun 15 09:55:00 2020 +0200

    Yet another ru update by Yuriy

 lib/doc/ru/Intro.lyx     |   12 +-
 lib/doc/ru/Tutorial.lyx  |    9 +-
 lib/doc/ru/UserGuide.lyx |  480 +++++++++++++++++++++++++++-------------------
 po/ru.po                 |   74 ++++----
 4 files changed, 335 insertions(+), 240 deletions(-)