fixed some style issues, added tooling for docs

docs/core/simulator.md

@@ -0,0 +1,27 @@
+# core/simulator.h
+
+## Free functions
+
+### `std::numeric_limits<InstanceId>::max();`
+### `std::numeric_limits<LinkId>::max();`
+
+## class Rng — public interface
+
+### `Simulator() = default;`
+### `static std::pair<InstanceId, Simulator *> create_simulator(InstanceId id);`
+### `static Simulator *get_simulator(InstanceId id) noexcept;`
+### `Time now() const noexcept;`
+### `EventId schedule_at(Time abs_time, F&& f, Args&&... args) { ... }`
+### `_event_pq.push(std::move(it));`
+### `EventId schedule_after(Time delay, F&& f, Args&&... args) { ... }`
+### `bool cancel(EventId id);`
+### `bool run_next();`
+### `void run_until(Time end_time);`
+### `void lock() noexcept;`
+### `bool is_locked() const noexcept { ... }`
+### `void flush_after(Time grace) noexcept;`
+### `Rng* create_rng(std::uint64_t seed);`
+### `Rng* get_rng() noexcept;`
+### `Rng const* get_rng() const noexcept;`
+### `Link* get_link(LinkId id) noexcept;`
+### `Link const* get_link(LinkId id) const noexcept;`