Added documentation for samecase. [Coke]++ for reviewing.

doc/Type/Cool.pod

@@ -1009,6 +1009,29 @@ With a customer filter too:
     say "have fun working on perl".wordcase(:filter(&uc), :where({ .chars > 3 }));
                                             # HAVE fun WORKING on PERL
 
+=head2 routine samecase
+
+Defined as:
+
+    sub samecase(Cool $string, Cool $pattern)
+    method samecase(Cool:D: Cool $pattern)
+
+Usage:
+
+    samecase STRING, PATTERN
+    STRING.samecase(PATTERN)
+
+Coerces the invocant (or in sub form, the first argument) to L<Str|/type/Str>, and returns a
+copy of C<$string> with case information for each individual character changed according to C<$pattern>. 
+(The pattern string can contain three types of characters, i.e. uppercase, lowercase and caseless. 
+For a given character in C<$pattern> its case information determines the case of the corresponding 
+character in the result.)
+If C<$string> is longer than C<$pattern>, the case information from the last character of 
+C<$pattern> is applied to the remaining characters of C<$string>.
+
+    say "perL 6".samecase("A__a__"); # Perl 6	
+    say "pERL 6".samecase("Ab");     # Perl 6
+
 =head2 routine uniname
 
 Defined as: