[algorithms.requirements] Add commas for readability

Author: jensmaurer

source/algorithms.tex

@@ -163,10 +163,10 @@
 
 \pnum
 When not otherwise constrained, the \tcode{BinaryPredicate} parameter is used
-whenever an algorithm expects a function object that when applied
+whenever an algorithm expects a function object that, when applied
 to the result of dereferencing two corresponding iterators or
 to dereferencing an iterator and type \tcode{T}
-when \tcode{T} is part of the signature
+when \tcode{T} is part of the signature,
 returns a value testable as \tcode{true}.
 In other words,
 if an algorithm takes \tcode{BinaryPredicate binary_pred} as its argument and