proper doc comments

src/buffer.rs

@@ -14,12 +14,12 @@ impl Buf {
         }
     }
 
-    // Truncate x and y and return a corresponding index into the data slice.
+    /// Truncate x and y and return a corresponding index into the data slice.
     const fn index(&self, x: f32, y: f32) -> usize {
         crate::util::index(self.width, self.height, x, y)
     }
 
-    // Get the buffer value at a given position. The implementation effectively treats data as periodic, hence any finite position will produce a value.
+    /// Get the buffer value at a given position. The implementation effectively treats data as periodic, hence any finite position will produce a value.
     pub fn get_buf(&self, x: f32, y: f32) -> f32 {
         self.buf[self.index(x, y)]
     }