Update build instructions to use upstream binary packages

[fmauch]

The build instructions are rather outdated, as we don't need to build any upstream packages from source anymore.

The old instructions have probably lead to issues like #413

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (foxy@55cb097). Click here to learn what that means.
The diff coverage is n/a.

@@          Coverage Diff           @@
##             foxy    #419   +/-   ##
======================================
  Coverage        ?   3.73%           
======================================
  Files           ?      16           
  Lines           ?    1071           
  Branches        ?     212           
======================================
  Hits            ?      40           
  Misses          ?     942           
  Partials        ?      89           

Flag	Coverage Δ
unittests	3.73% <0.00%> (?)

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[RobertWilbrandt]

This seems reasonable for foxy