Concise hint rebuilding meta model

Doc/Sda1/jpaintro.xml

@@ -93,18 +93,18 @@
                 </itemizedlist>
 
                 <tip>
-                  <para>Do not forget to build your meta model class
-                  <classname>Lecture_</classname> and manually delete the
-                  existing <classname>Airline_</classname> (unless
-                  re-factoring <classname>Airline</classname> to
-                  <classname>Lecture</classname>).</para>
+                  <para>Do not forget running <command>mvn</command>
+                  <parameter>generate-sources</parameter> (re)building your
+                  meta model class <classname>Lecture_</classname> and
+                  manually delete the existing class
+                  <classname>Airline_</classname>.</para>
                 </tip>
               </listitem>
 
               <listitem>
                 <para>Modify
                 <classname>jpaintro.university.SearchByIcao</classname> to
-                retrieve all lectures from the database having a title
+                retrieve all lectures from your database having a title
                 starting with the letter <quote>S</quote>.</para>
 
                 <tip>