Update the doxygen build_system.dcc file.

[KineticTheory]

• Fixes config/doc/build_system.dcc needs a re-write #501

Status

• Reference:
  • Pre-Merge Code Review
  • CDash Status
• Checks
  • Travis/Appveyor CI checks pass
  • Code coverage does not decrease
  • Valgrind test passes
  • Toss3 checks pass
  • Trinitite checks pass
  • Code reviewed/approved, sufficient DbC checks, testing, documentation

[codecov]

Codecov Report

Merging #1129 (16aad75) into develop (28c6658) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           develop   #1129   +/-   ##
=======================================
  Coverage     89.0%   89.0%           
=======================================
  Files          374     374           
  Lines        19261   19261           
=======================================
  Hits         17157   17157           
  Misses        2104    2104