Add more precise limitations of entity class and streams to README

[vitusortner]

No description provided.

[codecov]

Codecov Report

Merging #324 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #324   +/-   ##
========================================
  Coverage    81.40%   81.40%           
========================================
  Files           57       57           
  Lines         1479     1479           
========================================
  Hits          1204     1204           
  Misses         275      275           

Flag	Coverage Δ
#floor	81.40% <ø> (ø)
#floor_generator	80.95% <ø> (ø)

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