MS-FO-LC1-015: Better definition of term numeric

Class: Editorial      
 
section 6.2: Term "numeric": Use different font since it is not a true
type and give explanation of the following form: In this recommendation,
we use the pseudo-type numeric to indicate that a function may take any
of the numeric types as its argument. For example, a function f with the
signature f($x as numeric) as ... represents the following functions
signatures: f($x as xs:decimal) as..., f($x as xs:float) as..., f($x as
xs:double) as.... It is represented in a different font since it is not
part of the language but only used for definitional purposes.