[Core] [Docs] Remove travis-ci references (#13916)

docs/ja/README.md

@@ -6,7 +6,6 @@
 -->
 
 [![現在のバージョン](https://img.shields.io/github/tag/qmk/qmk_firmware.svg)](https://github.com/qmk/qmk_firmware/tags)
-[![ビルド状態](https://travis-ci.org/qmk/qmk_firmware.svg?branch=master)](https://travis-ci.org/qmk/qmk_firmware)
 [![Discord](https://img.shields.io/discord/440868230475677696.svg)](https://discord.gg/Uq7gcHh)
 [![ドキュメントの状態](https://img.shields.io/badge/docs-ready-orange.svg)](https://docs.qmk.fm)
 [![GitHub 貢献者](https://img.shields.io/github/contributors/qmk/qmk_firmware.svg)](https://github.com/qmk/qmk_firmware/pulse/monthly)