Use more precise language in Cool summary

Addresses #1095

Author: zoffixznet

doc/Type/Cool.pod6

@@ -2,13 +2,13 @@
 
 =TITLE class Cool
 
-=SUBTITLE Object that can be treated as either a string or number
+=SUBTITLE Object that can be treated as both a string and number
 
     class Cool is Any { }
 
 C<Cool>, also known as the B<C>onvenient B<OO> B<L>oop, is a base class
 employed by a number of built-in classes that can be meaningfully coerced
-to a string or a number. For example, an L<Array> can be used in mathematical
+to a string and a number. For example, an L<Array> can be used in mathematical
 operations, where its numerical representation is the number of elements it
 contains. At the same time, it can be concatenated to a string, where its
 stringy representation is all of its elements L<joined|/routine/join> by