* Update helpcontent2 from branch 'master'
  - tdf#123192 - Improve help for function ATAN2
    
    updated text in ATAN2 section of 04060106.xhp
    added coordinates-to-polar-01.svg
    changed example and image
    removed 'Important!', added 'radians'
    changed 'LibreOffice' to '%PRODUCTNAME'
    created new folder 'scalc' under 'media/helpimg/'
    moved coordinates-to-polar-01.svg to new folder
    and added the path/image name to Package_html_media.mk
    droped xml-lang="en-US" tag, removed 'Note',
    removed '<pre>' tag, did not add <embed> as
    Jenkins rejects it.
    
    Change-Id: I5cff6289e8ab25f511e7d31ba2d4ad733dea184a
    Reviewed-on: https://gerrit.libreoffice.org/67619
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>