Fix wrong links in REST POD

Bugzilla/WebService/Server/REST/Resources/Classification.pm

@@ -45,5 +45,5 @@ Bugzilla::Webservice::Server::REST::Resources::Classification - The Classificati
 This part of the Bugzilla REST API allows you to deal with the available Classifications.
 You will be able to get information about them as well as manipulate them.
 
-See L<Bugzilla::WebService::Bug> for more details on how to use this part
+See L<Bugzilla::WebService::Classification> for more details on how to use this part
 of the REST API.

Bugzilla/WebService/Server/REST/Resources/Product.pm

@@ -78,5 +78,5 @@ Bugzilla::Webservice::Server::REST::Resources::Product - The Product REST API
 This part of the Bugzilla REST API allows you to list the available Products and
 get information about them.
 
-See L<Bugzilla::WebService::Bug> for more details on how to use this part of
+See L<Bugzilla::WebService::Product> for more details on how to use this part of
 the REST API.

Bugzilla/WebService/Server/REST/Resources/User.pm

@@ -61,5 +61,5 @@ Bugzilla::Webservice::Server::REST::Resources::User - The User Account REST API
 This part of the Bugzilla REST API allows you to get User information as well
 as create User Accounts.
 
-See L<Bugzilla::WebService::Bug> for more details on how to use this part of
+See L<Bugzilla::WebService::User> for more details on how to use this part of
 the REST API.