Fix CI (again) (#4196)

docs/mkdocs/docs/api/adl_serializer/from_json.md

@@ -14,7 +14,7 @@ noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_
 -> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {}))
 ```
 
-This function is usually called by the [`get()`](../basic_json/get.md) function of the [basic_json](../basic_json)
+This function is usually called by the [`get()`](../basic_json/get.md) function of the [basic_json](../basic_json/index.md)
 class (either explicitly or via the conversion operators).
 
 1. This function is chosen for default-constructible value types.

docs/mkdocs/docs/api/adl_serializer/to_json.md

@@ -7,7 +7,7 @@ static auto to_json(BasicJsonType& j, TargetType && val) noexcept(
 -> decltype(::nlohmann::to_json(j, std::forward<TargetType>(val)), void())
 ```
 
-This function is usually called by the constructors of the [basic_json](../basic_json) class.
+This function is usually called by the constructors of the [basic_json](../basic_json/index.md) class.
 
 ## Parameters