Fix relative link in config description

The link pointed to a config option that has since been renamed to
allowed classes, instead of a list of regex-matched messages

lib/new_relic/agent/configuration/default_source.rb

@@ -2177,7 +2177,7 @@ def self.notify
           :public => true,
           :type => Boolean,
           :allowed_from_server => false,
-          :description => 'If true, the agent strips messages from all exceptions except those in the [allowlist](#strip_exception_messages-allowlist). Enabled automatically in [high security mode](/docs/accounts-partnerships/accounts/security/high-security).'
+          :description => 'If true, the agent strips messages from all exceptions except those in the [allowed classes list](#strip_exception_messages-allowed_classes). Enabled automatically in [high security mode](/docs/accounts-partnerships/accounts/security/high-security).'
         },
         :'strip_exception_messages.allowed_classes' => {
           :default => '',