grassmods_ko.po: add Plural-Forms definition

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@66857 15284696-431f-4ddb-bdfa-cd5b030d7da7

locale/po/grassmods_ko.po

@@ -15,6 +15,7 @@ msgstr ""
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=1; plural=0;\n"
 
 #: ../db/drivers/mysql/index.c:55 ../db/drivers/sqlite/index.c:77
 #, fuzzy