Update README.md: note on layout being different to public OSMD, JustifiedMusicSystemBuilder used by default (#104)

not really related to #104 but kind of relevant and should be noted.

README.md

@@ -12,6 +12,9 @@ so take a look at the [OSMD Readme (and Wiki)](https://github.com/opensheetmusic
 
 For some tips and tricks using the audio player and osmd-extended specifically, look at this issue: https://github.com/opensheetmusicdisplay/osmd-extended/issues/62
 
+Also note that the layout might be slightly different to public OSMD because we currently use the JustifiedMusicSystemBuilder here, which is exclusive to the sponsor repository and creates justified blocks to try to make systems equally filled and measures similarly stretched.<br>
+You can turn this off and get the public OSMD layout via `osmd.EngravingRules.UseJustifiedBuilder = false`.
+
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