chore: add indonesian books and courses (#9827)
* chore: add indonesian books and courses
* fix: remove trailing slash
* 217:3-217:51 warning Remove trailing slash (https://belajar-rust.vercel.app) no-url-trailing-slash remark-lint
* 218:3-218:73 warning Remove trailing slash (https://dasarpemrogramanrust.novalagung.com) no-url-trailing-slash remark-lint