* studentTTest function description
* welchttest description, links in studentttest
* mannWhitneyUTest description
* Text changed slightly
* Text changed slightly
* Text changed slightly
* Text changed slightly
* - First header is first level.
- sample_index type set to UInt64.
- Return values renamed.
- mannWhitneyUTest:
- added continuity_correction parameter
- optional parameters wrapped in braces [ ]
- description refactored
- example SQL placed on single line
* Improved formulations (hopefully)
General data type names used (Integer, Float, Decimal)
Removed names from return values
* Fixes
* Optional parameters stated explicitly
* New line at the end of files
* Russian function description
* Files moved in the right folder
* Translated 'Original article' to russian
* Typos are fixed
* fixed alowed parameter value: "two sided" -> "two-sided"
* duplicate word "require" is removed from exception messages
* mannWhitneyUTest description changed
Added Tuple link in return values
"samples from two populations" added in short descriptions
* Russian translation updated
* fix
Co-authored-by: Alexey Smirnov <alexey-sm@yandex-team.ru>