clarify numeric literals

Author: JohnBrinkman

doc/spec.adoc

@@ -303,8 +303,8 @@ fragment EXP
 
 Number literals follow the same syntax rules as numeric values in JSON with three exceptions:
 
-1. Number literals may omit a leading zero.  For example, `.123` is not valid JSON, but is allowed as a number literal.
-2. Number literals may include a leading zero.  For example, `0123` is not valid JSON, but is allowed as a number literal.
+1. Number literals may omit a leading zero before the decimal point.  For example, `.123` is not valid JSON, but is allowed as a number literal.
+2. Number literals may include leading zeros ahead of the integral part of the number.  For example, `0123` is not valid JSON, but is allowed as a number literal.
 3. The grammar construction for a number literal does not include a minus sign.  Literal expressions are made negative by prefixing them with a unary minus.
 
 Note that number literals (and JSON numbers) allow scientific notation.