banana-bread.md: Remove optional sugar comment

It gets confusing as I'm about to add measurements for milliliters
etc...

Signed-off-by: Alan Orth <alan.orth@gmail.com>

banana-bread.md

@@ -5,7 +5,7 @@ Originally from: http://www.simplyrecipes.com/recipes/banana_bread/
 
 - 3 or 4 ripe bananas, mashed
 - 1/3 cup melted butter
-- 3/4 cup sugar (or 1/2!)
+- 3/4 cup sugar
 - 1 egg, beaten
 - 1 teaspoon vanilla
 - 1 teaspoon baking soda