[vz-dev] [volkszaehler/vzlogger] fddf47: make Dockerfile two stages

[StefanSchoof]

  Branch: refs/heads/master
  Home:   https://github.com/volkszaehler/vzlogger
  Commit: fddf47998843ad5e40b210b054ee5f6cce81f823
      https://github.com/volkszaehler/vzlogger/commit/fddf47998843ad5e40b210b054ee5f6cce81f823
  Author: StefanSchoof <4662023+StefanSchoof at users.noreply.github.com>
  Date:   2021-03-30 (Tue, 30 Mar 2021)

  Changed paths:
    M Dockerfile

  Log Message:
  -----------
  make Dockerfile two stages
run in user context
add foreground option

Add comment about static libsml

fix grammer in comment