docs: use doc comment for use_integers_for_enums (#117)

Co-authored-by: Andrew Lamb <[email protected]>

pbjson-build/src/lib.rs

@@ -186,7 +186,8 @@ impl Builder {
         self.emit_fields = true;
         self
     }
-    // print integers instead of enum names.
+
+    /// Print integers instead of enum names.
     pub fn use_integers_for_enums(&mut self) -> &mut Self {
         self.use_integers_for_enums = true;
         self