pandoc-quotes: Change default Russian quote marks

Per SE question chain, highly upvoted results, and repeated requests to
get the defaults here changed:

* https://russian.stackexchange.com/questions/1470/quotation-marks
* https://www.artlebedev.ru/kovodstvo/sections/104/
* https://ru.m.wikipedia.org/wiki/%D0%9A%D0%B0%D0%B2%D1%8B%D1%87%D0%BA%D0%B8
* odkr/pandoc-quotes.lua#10
* odkr/pandoc-quotes.lua#12

Closes #286

Co-authored-by: Wolf-SO <peu@rekoba.de>

Author: alerque

pandoc-quotes.lua/pandoc-quotes.lua

@@ -278,7 +278,7 @@ QUOT_MARKS_BY_LANG = {
     pt          = {'«',  '»',     '“',  '”'    },
     rm          = {'«',  '»',     '‹',  '›'    },
     ro          = {'„',  '”',     '«',  '»'    },
-    ru          = {'«',  '»',     '“',  '”'    },
+    ru          = {'«',  '»',     '„',  '“'    },
     sk          = {'„',  '“',     '‚',  '‘'    },
     sl          = {'„',  '“',     '‚',  '‘'    },
     sq          = {'„',  '“',     '‚',  '‘'    },