Add Polish to the list of available languages. Forgotten by mistake.

resources/qml/Preferences/GeneralPage.qml

@@ -170,7 +170,7 @@ UM.PreferencesPage
                             append({ text: "日本語", code: "ja_JP" })
                             append({ text: "한국어", code: "ko_KR" })
                             append({ text: "Nederlands", code: "nl_NL" })
-                            //Polish is disabled for being incomplete: append({ text: "Polski", code: "pl_PL" })
+                            append({ text: "Polski", code: "pl_PL" })
                             append({ text: "Português do Brasil", code: "pt_BR" })
                             append({ text: "Português", code: "pt_PT" })
                             append({ text: "Русский", code: "ru_RU" })