🔨 fix doxygen link

README.md

@@ -12,7 +12,7 @@
 [![Language grade: C/C++](https://img.shields.io/lgtm/grade/cpp/g/nlohmann/json.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/nlohmann/json/context:cpp)
 [![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/json.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:json)
 [![Try online](https://img.shields.io/badge/try-online-blue.svg)](https://wandbox.org/permlink/3lCHrFUZANONKv7a)
-[![Documentation](https://img.shields.io/badge/docs-doxygen-blue.svg)](https://nlohmann.github.io/json)
+[![Documentation](https://img.shields.io/badge/docs-doxygen-blue.svg)](https://nlohmann.github.io/json/doxygen/index.html)
 [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/nlohmann/json/master/LICENSE.MIT)
 [![FOSSA Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2Fnlohmann%2Fjson.svg?type=shield)](https://app.fossa.com/projects/git%2Bgithub.com%2Fnlohmann%2Fjson?ref=badge_shield)
 [![GitHub Releases](https://img.shields.io/github/release/nlohmann/json.svg)](https://github.com/nlohmann/json/releases)