fixed some style issues, added tooling for docs

docs/core/node.md

@@ -0,0 +1,13 @@
+# core/node.h
+
+## class Node — public interface
+
+### `Node(Simulator *const sim, NodeId id, NodeType type) noexcept;`
+### `virtual ~Node() = default;`
+### `NodeId id() const noexcept;`
+### `NodeStatus status() const noexcept;`
+### `NodeType type() const noexcept;`
+### `void set_status(NodeStatus s) noexcept;`
+### `void boot(Time boottime_ns);`
+### `void reboot(Time boottime_ns);`
+### `Node(const Node &) = delete;`