Add std::exception to the docs

doc/api.md

@@ -497,10 +497,13 @@ chrono-format-specifications).
 - [`std::atomic_flag`](https://en.cppreference.com/w/cpp/atomic/atomic_flag)
 - [`std::bitset`](https://en.cppreference.com/w/cpp/utility/bitset)
 - [`std::error_code`](https://en.cppreference.com/w/cpp/error/error_code)
+- [`std::exception`](https://en.cppreference.com/w/cpp/error/exception)
 - [`std::filesystem::path`](https://en.cppreference.com/w/cpp/filesystem/path)
-- [`std::monostate`](https://en.cppreference.com/w/cpp/utility/variant/monostate)
+- [`std::monostate`](
+  https://en.cppreference.com/w/cpp/utility/variant/monostate)
 - [`std::optional`](https://en.cppreference.com/w/cpp/utility/optional)
-- [`std::source_location`](https://en.cppreference.com/w/cpp/utility/source_location)
+- [`std::source_location`](
+  https://en.cppreference.com/w/cpp/utility/source_location)
 - [`std::thread::id`](https://en.cppreference.com/w/cpp/thread/thread/id)
 - [`std::variant`](https://en.cppreference.com/w/cpp/utility/variant/variant)