Update sample code in documentation

Author: cheonjaeung

docs/layout-composables.md

@@ -24,7 +24,7 @@ BoxGrid(
     Item(modifier = Modifier.row(1))
 
     // It will be placed at 1, 2.
-    Item(modifier = Modifier.column(1).row(2))
+    Item(modifier = Modifier.position(row = 2, column = 1))
 
     // It will be placed at 2, 0.
     Itme(modifier = Modifier.column(2))

docs/span.md

@@ -14,7 +14,7 @@ BoxGrid(
 ) {
     Item(modifier = Modifier.span { BoxGridItemSpan(row = 2) })
     Item(modifier = Modifier.column(2))
-    Item(modifier = Modifier.row(1).column(1).span { BoxGridItemSpan(column = 2) })
+    Item(modifier = Modifier.position(row = 1, column = 1).span { BoxGridItemSpan(column = 2) })
     Item(modifier = Modifier.row(2)span { BoxGridItemSpan(column = 2) })
 }
 ```