provide better docs for ndarray

Cargo.toml

@@ -2,7 +2,7 @@
 name = "eccodes"
 description = "Unofficial high-level Rust bindings of the latest ecCodes release"
 repository = "https://github.com/ScaleWeather/eccodes"
-version = "0.10.3"
+version = "0.10.4"
 readme = "README.md"
 authors = ["Jakub Lewandowski <[email protected]>"]
 keywords = ["eccodes", "grib", "bufr", "meteorology", "weather"]

src/message_ndarray.rs

@@ -22,9 +22,15 @@ impl KeyedMessage {
     /// Converts the message to a 2D ndarray.
     ///
     /// Returns ndarray where first dimension represents y coordinates and second dimension represents x coordinates,
-    /// ie. `[lat, lon]`. Index `[0, 0]` is the top-left corner of the grid:
+    /// ie. `[lat, lon]`. 
+    /// 
+    /// Common convention for grib files on regular lon-lat grid assumes that: 
+    /// index `[0, 0]` is the top-left corner of the grid:
     /// x coordinates are increasing with the i index,
     /// y coordinates are decreasing with the j index.
+    /// 
+    /// This convention can be checked with `iScansNegatively` and `jScansPositively` keys - 
+    /// if both are false, the above convention is used.
     ///
     /// Requires the keys `Ni`, `Nj` and `values` to be present in the message.
     ///