add a missing \n to pl translation i had removed previously by accident

doc/po/pl.po

@@ -1111,7 +1111,7 @@ msgid ""
 "<!-- TRANSLATOR: This is the section header for the following paragraphs - comparable\n"
 "     to the other headers like NAME and DESCRIPTION and should therefore be uppercase. -->\n"
 "<!ENTITY translation-title \"TRANSLATION\">\n"
-msgstr "<!ENTITY translation-title \"TŁUMACZENIE\">"
+msgstr "<!ENTITY translation-title \"TŁUMACZENIE\">\n"
 
 #. type: Plain text
 #: apt.ent:382