Allow examples to compile

Author: coke

doc/Type/CompUnit/Repository/FileSystem.pod6

@@ -4,6 +4,7 @@
 
 =SUBTITLE CompUnit::Repository::FileSystem
 
+=for code :preamble<role CompUnit::Repository::Locally {}; role CompUnit::Repository {};>
     class CompUnit::Repository::FileSystem
         does CompUnit::Repository::Locally
         does CompUnit::Repository

doc/Type/CompUnit/Repository/Installation.pod6

@@ -4,6 +4,7 @@
 
 =SUBTITLE CompUnit::Repository::Installation
 
+=for code :preamble<role CompUnit::Repository::Locally {}; role CompUnit::Repository::Installable {}>
     class CompUnit::Repository::Installation
         does CompUnit::Repository::Locally
         does CompUnit::Repository::Installable
@@ -86,6 +87,7 @@ matching C<$spec>.
 
 =head2 method need
 
+=for code :method :preamble<method !precomp-stores() {}; method precomp-repository() {}>
     method need(
         CompUnit::DependencySpecification $spec,
         CompUnit::PrecompilationRepository $precomp = self.precomp-repository(),

doc/Type/IO/CatHandle.pod6

@@ -21,6 +21,7 @@ usable anywhere a read-only L<IO::Handle> can be used.
 
 Defined as:
 
+=for code :method
     method new(*@handles, :&on-switch, :$chomp = True,
                :$nl-in = ["\n", "\r\n"], Str :$encoding, Bool :$bin)
 

doc/Type/Signature.pod6

@@ -1050,6 +1050,7 @@ Throws C<X::Cannot::Capture>.
 
 =head1 Runtime creation of Signature objects (6.d, 2019.01 and later)
 
+=for code :preamble<role Type {}>
     Signature.new(params => (...), returns => Type, arity => 1, count => 1)
 
 In some situations, specifically when working with the MetaObject Protocol,