moved files out of subdirectories, added required documentation

src/dragon.h

@@ -0,0 +1,17 @@
+#ifndef __DRAGON_H__
+#define __DRAGON_H__
+
+#include "enemy.h"
+
+class dragon final: public enemy_base {
+        const position guards;
+public:
+        dragon(RNG *rng, const feature enabled_features, const position &pos,
+               const int gen_room_num, const position &guards);
+        const char *get_race_name() const override;
+        long_result act(level *lvl, character *pc, bool hostile) override;
+        int dies(level *lvl) override;
+        position get_guards() const;
+};
+
+#endif