added Rösti picture, fixed smaller typos (#572)

src/roesti.md

@@ -1,5 +1,8 @@
 # Rösti
 
+![Rösti](pix/roesti.webp)
+Used two serving sizes for this Rösti
+
 This swiss classic works great together with fried eggs and steamed peas or spinach.
 Can be useful to get rid of leftover potatoes from the day before.
 
@@ -13,7 +16,7 @@ Can be useful to get rid of leftover potatoes from the day before.
 - 2 carrots
 - 500g (~1lb) peas or spinach
 - 4 eggs
-- 2 onion (medium size)
+- 2 onions (medium size)
 - butter
 
 ## Directions