Add documentation about (lack of) dcc support

[Zarthus]

Fix #93

[mbax]

Hah!

[codecov-io]

Codecov Report

Merging #232 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #232   +/-   ##
=========================================
  Coverage     31.19%   31.19%           
  Complexity      492      492           
=========================================
  Files           216      216           
  Lines          4241     4241           
  Branches        453      453           
=========================================
  Hits           1323     1323           
  Misses         2865     2865           
  Partials         53       53

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[mbax]

Could be considered later, but for now not adding it.