man: add "History" sections for removed settings

The general idea is that users should be able to figure out if some option
that they see in a config file or on some internet page is something that
systemd knows about. Once users know that, yes, this was an option but has
been deprecated and removed from the documentation, it's much easier for them
to find any docs in old versions if they want to. Or to switch to something
different.

man/kernel-command-line.xml

@@ -557,7 +557,19 @@
         the hostname, it simply controls the initial hostname set during early boot.</para></listitem>
       </varlistentry>
     </variablelist>
+  </refsect1>
 
+  <refsect1>
+      <title>History</title>
+
+      <variablelist>
+        <varlistentry>
+          <term>systemd 252</term>
+          <listitem><para>Kernel command-line arguments <varname>systemd.unified_cgroup_hierarchy</varname>
+          and <varname>systemd.legacy_systemd_cgroup_controller</varname> were deprecated. Please switch to
+          the unified cgroup hierarchy.</para></listitem>
+        </varlistentry>
+      </variablelist>
   </refsect1>
 
   <refsect1>

man/systemd-system.conf.xml

@@ -592,6 +592,18 @@
       </table>
   </refsect1>
 
+  <refsect1>
+      <title>History</title>
+
+      <variablelist>
+        <varlistentry>
+          <term>systemd 252</term>
+          <listitem><para>Option <varname>DefaultBlockIOAccounting=</varname> was deprecated. Please switch
+          to the unified cgroup hierarchy.</para></listitem>
+        </varlistentry>
+      </variablelist>
+  </refsect1>
+
   <refsect1>
       <title>See Also</title>
       <para>

man/systemd.resource-control.xml

@@ -1103,6 +1103,31 @@ DeviceAllow=/dev/loop-control
     </variablelist>
   </refsect1>
 
+  <refsect1>
+      <title>History</title>
+
+      <variablelist>
+        <varlistentry>
+          <term>systemd 252</term>
+          <listitem><para> Options for controlling the Legacy Control Group Hierarchy (<ulink
+          url="https://docs.kernel.org/admin-guide/cgroup-v1/index.html">Control Groups version 1</ulink> are
+          now fully deprecated: <varname>CPUShares=<replaceable>weight</replaceable></varname>,
+          <varname>StartupCPUShares=<replaceable>weight</replaceable></varname>,
+          <varname>MemoryLimit=<replaceable>bytes</replaceable></varname>,
+          <varname>BlockIOAccounting=</varname>,
+          <varname>BlockIOWeight=<replaceable>weight</replaceable></varname>,
+          <varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname>,
+          <varname>BlockIODeviceWeight=<replaceable>device</replaceable>
+          <replaceable>weight</replaceable></varname>,
+          <varname>BlockIOReadBandwidth=<replaceable>device</replaceable>
+          <replaceable>bytes</replaceable></varname>,
+          <varname>BlockIOWriteBandwidth=<replaceable>device</replaceable>
+          <replaceable>bytes</replaceable></varname>.
+          Please switch to the unified cgroup hierarchy.</para></listitem>
+        </varlistentry>
+      </variablelist>
+  </refsect1>
+
   <refsect1>
     <title>See Also</title>
     <para>

man/systemd.xml

@@ -1251,6 +1251,19 @@
     </variablelist>
   </refsect1>
 
+  <refsect1>
+      <title>History</title>
+
+      <variablelist>
+        <varlistentry>
+          <term>systemd 252</term>
+          <listitem><para>Kernel command-line arguments <varname>systemd.unified_cgroup_hierarchy</varname>
+          and <varname>systemd.legacy_systemd_cgroup_controller</varname> were deprecated. Please switch to
+          the unified cgroup hierarchy.</para></listitem>
+        </varlistentry>
+      </variablelist>
+  </refsect1>
+
   <refsect1>
     <title>See Also</title>
     <para>