Added Serbian typography rules (#6596)

(required crengine bump in next commit)

frontend/apps/reader/modules/readertypography.lua

@@ -41,6 +41,7 @@ local HYPH_DICT_NAME_TO_LANG_NAME_TAG = {
     ["Russian_EnGB.pattern"] = { _("Russian + English (UK)"), "ru-GB" },
     ["Russian_EnUS.pattern"] = { _("Russian + English (US)"), "ru-US" },
     ["Russian.pattern"]      = { _("Russian"),      "ru" },
+    ["Serbian.pattern"]      = { _("Serbian"),      "sr" },
     ["Slovak.pattern"]       = { _("Slovak"),       "sk" },
     ["Slovenian.pattern"]    = { _("Slovenian"),    "sl" },
     ["Spanish.pattern"]      = { _("Spanish"),      "es" },
@@ -86,6 +87,7 @@ local LANGUAGES = {
     { "ru-GB",                 {},   "Hb  ",   _("Russian + English (UK)") },
     { "ru-US",                 {},   "Hb  ",   _("Russian + English (US)") },
     { "ru",               {"rus"},   "Hb  ",   _("Russian") },
+    { "sr",               {"srp"},   "H   ",   _("Serbian") },
     { "sk",               {"slk"},   "HB  ",   _("Slovak") },
     { "sl",               {"slv"},   "H   ",   _("Slovenian") },
     { "es",               {"spa"},   "Hb  ",   _("Spanish") },