fix: confusing wording for billing cycle

docs: update screenshots on readme

includes/i18n/jp.php

@@ -42,6 +42,10 @@ $i18n = [
     "Weekly"          => "毎週",
     "Monthly"         => "毎月",
     "Yearly"          => "毎年",
+    "daily"           => "日",
+    "weekly"          => "週",
+    "monthly"         => "月",
+    "yearly"          => "年",
     "days"            => "日毎",
     "weeks"           => "週毎",
     "months"          => "月毎",
@@ -58,7 +62,7 @@ $i18n = [
     "search_logo"     => "ウェブ上でロゴを検索する",
     "web_search"      => "ウェブ検索",
     "currency"        => "通貨",
-    "billing_cycle"   => "請求サイクル",
+    "payment_every"   => "支払い頻度",
     "frequency"       => "頻度",
     "cycle"           => "サイクル",
     "next_payment"    => "次回支払い",