Updated nlohmann::basic_json (markdown)

nlohmann::basic_json.md

@@ -125,7 +125,8 @@ returns the maximum possible number of elements
 
 - [**erase**](https://github.com/nlohmann/json/wiki/nlohmann::basic_json::erase)<br>
 erases elements
-- `clear`
+- [**clear**](https://github.com/nlohmann/json/wiki/nlohmann::basic_json::clear)<br>
+clears the contents
 - `push_back`
 - `operator+=`
 - `swap`