nixos/prometheus-exporters: minor doc improvements

* Content of `programlisting` shouldn't be indented, otherwise it's
  weirdly indented in the output.
* Use `<xref linkend=.../>` in the release notes: then users can
  directly go to the option documentation when reading release notes.
* Don't use docbook tags in `mkRemovedOptionModule`: it's only used
  during evaluation where docbook isn't rendered.

nixos/doc/manual/release-notes/rl-2103.xml

@@ -304,7 +304,7 @@
        <literal>/probe</literal> endpoint.
        In the prometheus scrape configuration the scrape target might look like this:
        <programlisting>
-       http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/endpoint
+http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/endpoint
        </programlisting>
      </para>
      <para>
@@ -313,7 +313,7 @@
        in the corresponding NixOS test.
      </para>
      <para>
-       These changes also affect <literal>services.prometheus.exporters.rspamd</literal>, which is
+       These changes also affect <xref linkend="opt-services.prometheus.exporters.rspamd.enable" />, which is
        just a preconfigured instance of the json exporter.
      </para>
      <para>

nixos/modules/services/monitoring/prometheus/exporters/json.nix

@@ -4,7 +4,6 @@ with lib;
 
 let
   cfg = config.services.prometheus.exporters.json;
-
 in
 {
   port = 7979;
@@ -30,15 +29,14 @@ in
     (mkRemovedOptionModule [ "url" ] ''
       This option was removed. The URL of the endpoint serving JSON
       must now be provided to the exporter by prometheus via the url
-      parameter <literal>target</literal>.
+      parameter `target'.
 
       In prometheus a scrape URL would look like this:
-      <programlisting>
-      http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/endpoint
-      </programlisting>
 
-      For more information, take a look at the <link xlink:href="https://github.com/prometheus-community/json_exporter">
-      official documentation</link> of the json_exporter.
+        http://some.json-exporter.host:7979/probe?target=https://example.com/some/json/endpoint
+
+      For more information, take a look at the official documentation
+      (https://github.com/prometheus-community/json_exporter) of the json_exporter.
     '')
      ({ options.warnings = options.warnings; options.assertions = options.assertions; })
   ];

nixos/modules/services/monitoring/prometheus/exporters/rspamd.nix

@@ -85,15 +85,14 @@ in
     (mkRemovedOptionModule [ "url" ] ''
       This option was removed. The URL of the rspamd metrics endpoint
       must now be provided to the exporter by prometheus via the url
-      parameter <literal>target</literal>.
+      parameter `target'.
 
       In prometheus a scrape URL would look like this:
-      <programlisting>
-      http://some.rspamd-exporter.host:7980/probe?target=http://some.rspamd.host:11334/stat
-      </programlisting>
 
-      For more information, take a look at the <link xlink:href="https://github.com/prometheus-community/json_exporter">
-      official documentation</link> of the json_exporter.
+        http://some.rspamd-exporter.host:7980/probe?target=http://some.rspamd.host:11334/stat
+
+      For more information, take a look at the official documentation
+      (https://github.com/prometheus-community/json_exporter) of the json_exporter.
     '')
      ({ options.warnings = options.warnings; options.assertions = options.assertions; })
   ];