move Observium plugin outside of Netdisco dist

Netdisco/lib/App/Netdisco/Manual/ReleaseNotes.pod

@@ -35,6 +35,13 @@ but they are backwards compatible.
 
 =back
 
+=head1 2.020000
+
+=head2 General Notices
+
+If you were using the C<X::Observium> plugin, you'll now need to install
+the separate distribution L<App::NetdiscoX::Web::Plugin::Observium>.
+
 =head1 2.019000
 
 =head2 General Notices

Netdisco/lib/App/Netdisco/Manual/WritingPlugins.pod

@@ -296,7 +296,8 @@ path. We recommend use of the L<File::ShareDir> module to package and ship
 templates along with your plugin, as shown.
 
 Each path added using C<register_template_path> is searched I<before> any
-existing paths in the template config.
+existing paths in the template config. See the
+L<App::NetdiscoX::Web::Plugin::Observium> distribution for a working example.
 
 =head2 Template Variables
 

Netdisco/lib/App/Netdisco/Web/Plugin.pm

@@ -3,6 +3,8 @@ package App::Netdisco::Web::Plugin;
 use Dancer ':syntax';
 use Dancer::Plugin;
 
+use Path::Class 'dir';
+
 set(
   '_additional_css'         => [],
   '_additional_javascript'  => [],
@@ -28,7 +30,7 @@ register 'register_template_path' => sub {
 
   unshift
     @{ config->{engines}->{template_toolkit}->{INCLUDE_PATH} },
-    $path;
+    $path, dir($path, 'views')->stringify;
 };
 
 sub _register_include {