DOC: clarified translation functionality in demodb docs

Author: Liudmila Mantrova

doc/src/sgml/demodb-bookings.sgml

@@ -754,9 +754,9 @@ Referenced by:
    <para>
     Some fields in the demo database are available in English and Russian.
     Translations to other languages are not provided, but are easy to add.
-    The <function>bookings.lang</function> function selects the language
-    in which to display these fields, returning the value of the
-    <parameter>bookings.lang</parameter> parameter.
+    The <function>bookings.lang</function> returns the value of the
+    <parameter>bookings.lang</parameter> parameter, that is, the language
+    in which these fields will be displayed.
    </para>
 
    <para>
@@ -811,6 +811,9 @@ ALTER DATABASE demo SET bookings.lang = en;
     For other methods of settings configuration parameters,
     see <xref linkend="config-setting">.
    </para>
+
+   <para>In the examples below, the English language is selected for translatable fields.
+   </para>
   </sect2>
 
 
@@ -822,7 +825,7 @@ ALTER DATABASE demo SET bookings.lang = en;
    </para>
 
    <para>
-    The results displayed below were received on a small database version (demo_small) of August 15, 2017.
+    The results displayed below were received on a small database version (demo-small) of August 15, 2017.
     If the same queries return different data on your system,
     check your demo database version  (using the <function>bookings.now</function> function).
     Some minor deviations may be caused by the difference between your local time and Moscow time,