moved files out of subdirectories, added required documentation

src/restore_health.h

@@ -0,0 +1,16 @@
+#ifndef __RESTORE_HEALTH_H__
+#define __RESTORE_HEALTH_H__
+
+#include "potion.h"
+
+class restore_health final: public potion {
+        static const int GAIN_HEALTH = 10;
+public:
+        restore_health(const position &pos);
+        void apply(const enum race &race, int &HP, int &ATK, int &DEF,
+                   fraction &base_hit_rate) override;
+        int get_priority() const override;
+        const char *get_name() const override;
+};
+
+#endif