man: add .service suffix to systemd-pstore(8)

That is the pattern that we always use with executables not in
$PATH.

man/rules/meson.build

@@ -772,7 +772,7 @@ manpages = [
  ['systemd-nspawn', '1', [], ''],
  ['systemd-path', '1', [], ''],
  ['systemd-portabled.service', '8', ['systemd-portabled'], 'ENABLE_PORTABLED'],
- ['systemd-pstore', '8', ['systemd-pstore.service'], 'ENABLE_PSTORE'],
+ ['systemd-pstore.service', '8', ['systemd-pstore'], 'ENABLE_PSTORE'],
  ['systemd-quotacheck.service',
   '8',
   ['systemd-quotacheck'],

man/systemd-pstore.service.xml

@@ -7,19 +7,19 @@
           xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>
-    <title>systemd-pstore</title>
+    <title>systemd-pstore.service</title>
     <productname>systemd</productname>
   </refentryinfo>
 
   <refmeta>
-    <refentrytitle>systemd-pstore</refentrytitle>
+    <refentrytitle>systemd-pstore.service</refentrytitle>
     <manvolnum>8</manvolnum>
   </refmeta>
 
   <refnamediv>
-    <refname>systemd-pstore</refname>
     <refname>systemd-pstore.service</refname>
-    <refpurpose>Tool to archive contents of the persistent storage filesystem</refpurpose>
+    <refname>systemd-pstore</refname>
+    <refpurpose>A service to archive contents of pstore</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>