Remove perldoc style CAPS args.

Closes #4607

Author: coke

doc/Type/Str.rakudoc

@@ -549,15 +549,16 @@ multi method split(Str:D: List:D $delimiters, $limit = Inf,
 
 Splits a string up into pieces based on delimiters found in the string.
 
-If C<DELIMITER> is a string, it is searched for literally and not treated
-as a regex.  If C<DELIMITER> is the empty string, it effectively returns all
-characters of the string separately (plus an empty string at the begin and at
-the end).  If C<PATTERN> is a regular expression, then that will be used
-to split up the string.  If C<DELIMITERS> is a list, then all of its elements
-will be considered a delimiter (either a string or a regular expression) to
-split the string on.
-
-The optional C<LIMIT> indicates in how many segments the string should be
+If C<$delimiter> is a string, it is used literally. An empty string
+effectively returns all characters of the string separately (plus an
+empty string at the begin and at the end).
+
+C<$delimiter> also can be passed as a L<C<Regex>|/type/Regex>.
+
+If a list is used, then each of its elements
+will be considered a delimiter based on its type as mentioned above.
+
+The optional C<$limit> indicates in how many segments the string should be
 split, if possible.  It defaults to B<Inf> (or B<*>, whichever way you look at
 it), which means "as many as possible". Note that specifying negative limits
 will not produce any meaningful results.