Redirecting anchors and clarifying terms

Closes #3755, closes Raku/old-issue-tracker#6451

Author: JJ

doc/Language/5to6-nutshell.pod6

@@ -626,7 +626,7 @@ of a list, or in passing arguments to a sub that expects a flat list of
 C<KEY, VALUE, KEY, VALUE>, then continuing to use C«=>» may break your code.
 The easiest workaround is to change that I<fat arrow> to a regular comma, and
 manually add quotes to its left-hand side. Or, you can change the sub's API
-to L<slurp a hash|/type/Signature#Slurpy_(A.K.A._variadic)_parameters>.
+to L<slurp a hash|/type/Signature#Slurpy_parameters>.
 A better long-term solution is to change the sub's API to
 expect L<Pair|/type/Pair>s; however, this requires you to change
 all sub calls at once.

doc/Type/Parameter.pod6

@@ -149,7 +149,7 @@ Defined as:
     method slurpy(Parameter:D: --> Bool:D)
 
 Returns C<True> for
-L<slurpy parameters|/type/Signature#Slurpy_(A.K.A._variadic)_parameters>.
+L<slurpy parameters|/type/Signature#Slurpy_parameters>.
 
 =head2 method twigil
 
@@ -380,7 +380,7 @@ Defined as:
 
     method prefix(Parameter:D: --> Str:D)
 
-If the parameter is L«slurpy|/type/Signature#Slurpy_(A.K.A._variadic)_parameters»,
+If the parameter is L«slurpy|/type/Signature#Slurpy_variadic)_parameters»,
 returns the marker (e.g., C«*», C«**», or C«+») the parameter was declared
 with. Otherwise, returns an empty string.
 

doc/Type/Signature.pod6

@@ -256,7 +256,7 @@ against undefined values within the C<where> clause.
 
 =head3 Constraining slurpy arguments
 
-L<Slurpy arguments|#Slurpy_(A.K.A._variadic)_parameters> can not have type
+L<Slurpy arguments|#Slurpy_parameters> can not have type
 constraints. A C<where>-clause in conjunction with a L<Junction|/type/Junction>
 can be used to that effect.
 
@@ -648,11 +648,16 @@ directly apply string methods, such as the number of characters.
 X<|parameter,*@>
 X<|parameter,*%>
 X<|slurpy argument>
-=head2 Variadic parameters
+=head2 Slurpy parameters
 
 A function is X<variadic> if it can take a varying number of arguments; that is,
-its arity is not fixed. Therefore, optional, named, and slurpy parameters
-make routines that use them I<variadic>. An array or hash parameter can be
+its arity is not fixed. Therefore,
+L<optional|https://docs.raku.org/type/Signature#index-entry-optional_argument>,
+named, and slurpy parameters
+make routines that use them I<variadic>, and by extension are called variadic
+arguments. Here we will focus on slurpy parameters, or simply I<slurpies>.
+
+An array or hash parameter can be
 marked as I<slurpy> by leading single (*) or double asterisk (**) or a
 leading plus (+). A slurpy parameter can bind to an arbitrary number of
 arguments (zero or more), and it will result in a type that is compatible
@@ -695,7 +700,8 @@ say combined-slurpy(one => 1, two => 2, 3, 4, five => 5, 6);
 # OUTPUT: «{array => [3 4 6], hash => {five => 5, one => 1, two => 2}}␤»
 =end code
 
-Note that positional parameters aren't allowed after slurpy parameters:
+Note that positional parameters aren't allowed after slurpy (or, in
+fact, after any type of variadic) parameters:
 
 =begin code :skip-test<compile time error>
 :(*@args, $last);