Pull request #82: Whitespace also matters for binary operators.

Merge in DP/swift-book from whitespace_operator_70298068 to develop

Author: amartini51

ReferenceManual/LexicalStructure.rst

@@ -20,7 +20,7 @@ Whitespace and Comments
 -----------------------
 
 Whitespace has two uses: to separate tokens in the source file
-and to help determine whether an operator is a prefix or postfix
+and to distinguish between prefix, postfix, and binary operators
 (see :ref:`LexicalStructure_Operators`),
 but is otherwise ignored.
 The following characters are considered whitespace: