Added a few missing method definitions

doc/Type/Parameter.pod6

@@ -66,6 +66,10 @@ parameter (usually as an C<all>-Junction).
 
 =head2 method named
 
+Defined as:
+
+    method named(Parameter:D:) returns Bool:D
+
 Returns C<True> if it's a L<named parameter|/type/Signature#Positional_vs._Named>.
 
 =head2 method named_names
@@ -75,25 +79,45 @@ L<named parameter|/type/Signature#Positional_vs._Named>.
 
 =head2 method positional
 
+Defined as:
+
+    method positional(Parameter:D:) returns Bool:D
+
 Returns C<True> if the parameter is
 L<positional|/type/Signature#Positional_vs._Named>.
 
 =head2 method slurpy
 
+Defined as:
+
+    method slurpy(Parameter:D:) returns Bool:D
+
 Returns C<True> for
 L<slurpy parameters|/type/Signature#Slurpy_(A.K.A._Variadic)_Parameters>.
 
 =head2 method twigil
 
+Defined as:
+
+    method twigil(Parameter:D:) returns Str:D
+
 Returns a string containing the twigil part of the parameter's name.
 
 =head2 method optional
 
+Defined as:
+
+    method optional(Parameter:D:) returns Bool:D
+
 Returns C<True> for
 L<optional parameters|/type/Signature#Optional_and_Mandatory_Parameters>.
 
 =head2 method raw
 
+Defined as:
+
+    method raw(Parameter:D:) returns Bool:D
+
 Returns C<True> for raw parameters.
 
     sub f(\raw) {
@@ -122,6 +146,10 @@ their sigil in code.
 
 =head2 method capture
 
+Defined as:
+
+    method capture(Parameter:D:) returns Bool:D
+
 Returns C<True> for parameters that capture the rest of the argument list into
 a single L<Capture|/type/Capture> object.
 
@@ -135,20 +163,36 @@ declarations.
 
 =head2 method rw
 
+Defined as:
+
+    method rw(Parameter:D:) returns Bool:D
+
 Returns C<True> for L<C<is rw>|/type/Signature#Parameter_Traits_and_Modifiers>
 parameters.
 
 =head2 method copy
 
+Defined as:
+
+    method copy(Parameter:D:) returns Bool:D
+
 Returns C<True> for L<C<is copy>|/type/Signature#Parameter_Traits_and_Modifiers>
 parameters.
 
 =head2 method readonly
 
+Defined as:
+
+    method readonly(Parameter:D:) returns Bool:D
+
 Returns C<True> for read-only parameters (the default).
 
 =head2 method invocant
 
+Defined as:
+
+    method invocant(Parameter:D:) returns Bool:D
+
 Returns C<True> if the parameter is the
 L<invocant parameter|/type/Signature#Parameter_Separators>.