facet distribution: implement Display for OrderBy

milli/src/search/facet/facet_distribution.rs

@@ -1,4 +1,5 @@
 use std::collections::{BTreeMap, HashMap, HashSet};
+use std::fmt::Display;
 use std::ops::ControlFlow;
 use std::{fmt, mem};
 
@@ -37,6 +38,15 @@ pub enum OrderBy {
     Count,
 }
 
+impl Display for OrderBy {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            OrderBy::Lexicographic => f.write_str("alphabetically"),
+            OrderBy::Count => f.write_str("by count"),
+        }
+    }
+}
+
 pub struct FacetDistribution<'a> {
     facets: Option<HashMap<String, OrderBy>>,
     candidates: Option<RoaringBitmap>,