[DOC] update JndiContextSelector section; mention property `enableJndiContextSelector`
Note that in this case you must also set the "Log4jContextSelector" system property to
"<kbd>org.apache.logging.log4j.core.selector.JndiContextSelector</kbd>".
</p>
+ <p>For security reasons, from Log4j 2.17.0, JNDI must be enabled by setting system property <code>log4j2.enableJndiContextSelector=true</code>.</p>
</subsection>
<subsection name="Using Web Application Information During the Configuration">
<a name="WebLookup" />
