Fix newline rendering in Decidable chapter

src/plfa/part1/Decidable.lagda.md

@@ -595,8 +595,8 @@ fill in an implicit of an *empty* record type, since there aren't any fields
 after all. This is why `⊤` is defined as an empty record.
 
 The trick is to have an implicit argument of the type `T ⌊ n ≤? m ⌋`. Let's go
-through what this means step-by-step. First, we run the decision procedure, `n
-≤? m`. This provides us with evidence whether `n ≤ m` holds or not. We erase the
+through what this means step-by-step. First, we run the decision procedure,
+`n ≤? m`. This provides us with evidence whether `n ≤ m` holds or not. We erase the
 evidence to a boolean. Finally, we apply `T`. Recall that `T` maps booleans into
 the world of evidence: `true` becomes the unit type `⊤`, and `false` becomes the
 empty type `⊥`. Operationally, an implicit argument of this type works as a