apt_preferences(5): Correct default pin assignment documentation

This was broken, as higher pins were also assigned to versions
that are installed.

Closes: #623706

doc/apt_preferences.5.xml

@@ -115,12 +115,12 @@ from archives which in their <filename>Release</filename> files are marked as "N
 
 <varlistentry>
 <term>priority 500</term>
-<listitem><simpara>to the versions that are not installed and do not belong to the target release.</simpara></listitem>
+<listitem><simpara>to the versions that do not belong to the target release.</simpara></listitem>
 </varlistentry>
 
 <varlistentry>
 <term>priority 990</term>
-<listitem><simpara>to the versions that are not installed and belong to the target release.</simpara></listitem>
+<listitem><simpara>to the versions that belong to the target release.</simpara></listitem>
 </varlistentry>
 </variablelist>
 </para>