<replaceable> -> <emphasis>

Pandoc doesn't know <replaceable> so let's force it to be rendered as
italics.

doc/manual/command-ref/nix-shell.xml

@@ -19,20 +19,20 @@
 <refsynopsisdiv>
   <cmdsynopsis>
     <command>nix-shell</command>
-    <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
-    <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
+    <arg><option>--arg</option> <emphasis>name</emphasis> <emphasis>value</emphasis></arg>
+    <arg><option>--argstr</option> <emphasis>name</emphasis> <emphasis>value</emphasis></arg>
     <arg>
       <group choice='req'>
         <arg choice='plain'><option>--attr</option></arg>
         <arg choice='plain'><option>-A</option></arg>
       </group>
-      <replaceable>attrPath</replaceable>
+      <emphasis>attrPath</emphasis>
     </arg>
-    <arg><option>--command</option> <replaceable>cmd</replaceable></arg>
-    <arg><option>--run</option> <replaceable>cmd</replaceable></arg>
-    <arg><option>--exclude</option> <replaceable>regexp</replaceable></arg>
+    <arg><option>--command</option> <emphasis>cmd</emphasis></arg>
+    <arg><option>--run</option> <emphasis>cmd</emphasis></arg>
+    <arg><option>--exclude</option> <emphasis>regexp</emphasis></arg>
     <arg><option>--pure</option></arg>
-    <arg><option>--keep</option> <replaceable>name</replaceable></arg>
+    <arg><option>--keep</option> <emphasis>name</emphasis></arg>
     <group choice='req'>
       <arg choice='plain'>
         <group choice='req'>
@@ -41,12 +41,12 @@
         </group>
         <arg choice='plain' rep='repeat'>
           <group choice='req'>
-            <arg choice="plain"><replaceable>packages</replaceable></arg>
-            <arg choice="plain"><replaceable>expressions</replaceable></arg>
+            <arg choice="plain"><emphasis>packages</emphasis></arg>
+            <arg choice="plain"><emphasis>expressions</emphasis></arg>
           </group>
         </arg>
       </arg>
-      <arg><replaceable>path</replaceable></arg>
+      <arg><emphasis>path</emphasis></arg>
     </group>
   </cmdsynopsis>
 </refsynopsisdiv>
@@ -57,17 +57,17 @@
 dependencies of the specified derivation, but not the derivation
 itself.  It will then start an interactive shell in which all
 environment variables defined by the derivation
-<replaceable>path</replaceable> have been set to their corresponding
+<emphasis>path</emphasis> have been set to their corresponding
 values, and the script <literal>$stdenv/setup</literal> has been
 sourced.  This is useful for reproducing the environment of a
 derivation for development.</para>
 
-<para>If <replaceable>path</replaceable> is not given,
+<para>If <emphasis>path</emphasis> is not given,
 <command>nix-shell</command> defaults to
 <filename>shell.nix</filename> if it exists, and
 <filename>default.nix</filename> otherwise.</para>
 
-<para>If <replaceable>path</replaceable> starts with
+<para>If <emphasis>path</emphasis> starts with
 <literal>http://</literal> or <literal>https://</literal>, it is
 interpreted as the URL of a tarball that will be downloaded and
 unpacked to a temporary location. The tarball must include a single
@@ -103,10 +103,10 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
 <variablelist>
 
-  <varlistentry><term><option>--command</option> <replaceable>cmd</replaceable></term>
+  <varlistentry><term><option>--command</option> <emphasis>cmd</emphasis></term>
 
     <listitem><para>In the environment of the derivation, run the
-    shell command <replaceable>cmd</replaceable>. This command is
+    shell command <emphasis>cmd</emphasis>. This command is
     executed in an interactive shell. (Use <option>--run</option> to
     use a non-interactive shell instead.) However, a call to
     <literal>exit</literal> is implicitly added to the command, so the
@@ -118,7 +118,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
   </varlistentry>
 
-  <varlistentry><term><option>--run</option> <replaceable>cmd</replaceable></term>
+  <varlistentry><term><option>--run</option> <emphasis>cmd</emphasis></term>
 
     <listitem><para>Like <option>--command</option>, but executes the
     command in a non-interactive shell. This means (among other
@@ -127,10 +127,10 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
   </varlistentry>
 
-  <varlistentry><term><option>--exclude</option> <replaceable>regexp</replaceable></term>
+  <varlistentry><term><option>--exclude</option> <emphasis>regexp</emphasis></term>
 
     <listitem><para>Do not build any dependencies whose store path
-    matches the regular expression <replaceable>regexp</replaceable>.
+    matches the regular expression <emphasis>regexp</emphasis>.
     This option may be specified multiple times.</para></listitem>
 
   </varlistentry>
@@ -150,7 +150,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
   </varlistentry>
 
-  <varlistentry><term><option>--packages</option> / <option>-p</option> <replaceable>packages</replaceable>…</term>
+  <varlistentry><term><option>--packages</option> / <option>-p</option> <emphasis>packages</emphasis>…</term>
 
     <listitem><para>Set up an environment in which the specified
     packages are present.  The command line arguments are interpreted
@@ -162,7 +162,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
   </varlistentry>
 
-  <varlistentry><term><option>-i</option> <replaceable>interpreter</replaceable></term>
+  <varlistentry><term><option>-i</option> <emphasis>interpreter</emphasis></term>
 
     <listitem><para>The chained script interpreter to be invoked by
     <command>nix-shell</command>. Only applicable in
@@ -171,7 +171,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 
     </listitem></varlistentry>
 
-  <varlistentry><term><option>--keep</option> <replaceable>name</replaceable></term>
+  <varlistentry><term><option>--keep</option> <emphasis>name</emphasis></term>
 
     <listitem><para>When a <option>--pure</option> shell is started,
     keep the listed environment variables.</para></listitem>
@@ -278,13 +278,13 @@ following lines:
 
 <programlisting>
 #! /usr/bin/env nix-shell
-#! nix-shell -i <replaceable>real-interpreter</replaceable> -p <replaceable>packages</replaceable>
+#! nix-shell -i <emphasis>real-interpreter</emphasis> -p <emphasis>packages</emphasis>
 </programlisting>
 
-where <replaceable>real-interpreter</replaceable> is the “real” script
+where <emphasis>real-interpreter</emphasis> is the “real” script
 interpreter that will be invoked by <command>nix-shell</command> after
 it has obtained the dependencies and initialised the environment, and
-<replaceable>packages</replaceable> are the attribute names of the
+<emphasis>packages</emphasis> are the attribute names of the
 dependencies in Nixpkgs.</para>
 
 <para>The lines starting with <literal>#! nix-shell</literal> specify