[LyX/master] Update Russian documentation

[Juergen Spitzmueller]

commit 10bbf9e62b3544783515e448d063290d94a97661
Author: Yuriy Skalko <yuriy.skalko at gmail.com>
Date:   Sat Aug 1 03:01:34 2020 +0300

    Update Russian documentation

 lib/doc/ru/Intro.lyx     |   29 +++-
 lib/doc/ru/Math.lyx      |  101 +++++------
 lib/doc/ru/Tutorial.lyx  |    2 +-
 lib/doc/ru/UserGuide.lyx |  429 ++++++++++++++++++++++++++--------------------
 4 files changed, 311 insertions(+), 250 deletions(-)