man: mention the exclamation mark and minus sign literally, to make things searchable

I was looking for the explanation for the exclamation mark in the text,
and couldn't find it, searching for "!". Let's make this easier, and
indicate the character meant.

1 files changed, 8 insertions, 12 deletions

diff --git a/man/tmpfiles.d.xml b/man/tmpfiles.d.xml
index 90234c3d43..1e761e9b05 100644
--- a/man/tmpfiles.d.xml
+++ b/man/tmpfiles.d.xml
@@ -154,8 +154,8 @@ L     /tmp/foobar -    -    -     -   /dev/null</programlisting>
     <refsect2>
       <title>Type</title>
 
-      <para>The type consists of a single letter and optionally an
-      exclamation mark and/or minus sign.</para>
+      <para>The type consists of a single letter and optionally an exclamation mark (<literal>!</literal>)
+      and/or minus sign (<literal>-</literal>).</para>
 
       <para>The following line types are understood:</para>
 
@@ -453,13 +453,10 @@ L     /tmp/foobar -    -    -     -   /dev/null</programlisting>
         </varlistentry>
       </variablelist>
 
-      <para>If the exclamation mark is used, this line is only safe to
-      execute during boot, and can break a running system. Lines
-      without the exclamation mark are presumed to be safe to execute
-      at any time, e.g. on package upgrades.
-      <command>systemd-tmpfiles</command> will execute line with an
-      exclamation mark only if option <option>--boot</option> is
-      given.</para>
+      <para>If the exclamation mark (<literal>!</literal>) is used, this line is only safe to execute during
+      boot, and can break a running system. Lines without the exclamation mark are presumed to be safe to
+      execute at any time, e.g. on package upgrades. <command>systemd-tmpfiles</command> will take lines with
+      an exclamation mark only into consideration, if the <option>--boot</option> option is given.</para>
 
       <para>For example:
       <programlisting># Make sure these are created by default so that nobody else can
@@ -471,9 +468,8 @@ r! /tmp/.X[0-9]*-lock</programlisting>
       running system, and will only be executed with
       <option>--boot</option>.</para>
 
-      <para>If the minus sign is used, this line failing to run
-      successfully during create (and only create) will not cause
-      the execution of <command>systemd-tmpfiles</command> to return
+      <para>If the minus sign (<literal>-</literal>) is used, this line failing to run successfully during
+      create (and only create) will not cause the execution of <command>systemd-tmpfiles</command> to return
       an error.</para>
 
       <para>For example: