doc: improved wording in some places

Avoid "mountpoint mounted" (word repetition),
"queriable" (no match in m-w.com and dict.cc).

man/file-hierarchy.xml

@@ -63,7 +63,7 @@
     and restrictions systemd makes on the file system
     hierarchy.</para>
 
-    <para>Many of the paths described here are queriable
+    <para>Many of the paths described here can be queried
     with the
     <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>
     tool.</para>

man/systemd-escape.xml

@@ -64,7 +64,7 @@
     used to escape and to undo escaping of strings.</para>
 
     <para>The command takes any number of strings on the command line,
-    and will process them individually, one after the other. It will
+    and will process them individually, one after another. It will
     output them separated by spaces to stdout.</para>
 
     <para>By default, this command will escape the strings passed,

man/systemd-nspawn.xml

@@ -770,8 +770,8 @@
         <option>yes</option>, full volatile mode is enabled. This
         means the root directory is mounted as a mostly unpopulated
         <literal>tmpfs</literal> instance, and
-        <filename>/usr</filename> from the OS tree is mounted into it,
-        read-only (the system thus starts up with read-only OS
+        <filename>/usr</filename> from the OS tree is mounted into it
+        in read-only mode (the system thus starts up with read-only OS
         resources, but pristine state and configuration, any changes
         to the either are lost on shutdown). When the mode parameter
         is specified as <option>state</option>, the OS tree is

man/systemd-path.xml

@@ -60,7 +60,7 @@
     <para><command>systemd-path</command> may be used to query system
     and user paths. The tool makes many of the paths described in
     <citerefentry><refentrytitle>file-hierarchy</refentrytitle><manvolnum>7</manvolnum></citerefentry>
-    queriable.</para>
+    available for querying.</para>
 
     <para>When invoked without arguments, a list of known paths and
     their current values is shown. When at least one argument is

man/sysusers.d.xml

@@ -113,7 +113,7 @@ u root 0 "Superuser" /root</programlisting>
         <varlistentry>
           <term><varname>m</varname></term>
           <listitem><para>Add a user to a group. If the user or group
-          are not existing yet, they will be implicitly
+          do not exist yet, they will be implicitly
           created.</para></listitem>
         </varlistentry>