[rygel] doc: Add note regarding blacklisting behavior

[Jens Georg <jensgeorg src gnome org>]

commit 4a0e09a37e0ef70207e4c14fe6c8b980dc8ba628
Author: Jens Georg <mail jensge org>
Date:   Mon Jan 14 14:14:05 2019 +0100

    doc: Add note regarding blacklisting behavior

 doc/man/rygel.conf.xml | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/doc/man/rygel.conf.xml b/doc/man/rygel.conf.xml
index a64aab5f..8367e333 100644
--- a/doc/man/rygel.conf.xml
+++ b/doc/man/rygel.conf.xml
@@ -405,6 +405,9 @@ man(1), man(7), http://www.tldp.org/HOWTO/Man-Page/
           <para><note>
               <para>If you enter a normal path that contains whitespace there is no need to escape them with 
either a backslash or putting the string in quotes.</para>
             </note></para>
+            <para><note>
+                    <para>It is strongly advised against using an exported folder as a target for downloads 
when <userinput>extract-metadata</userinput> is enabled. Rygel will most likely blacklist the files then 
because they will fail to extract.</para>
+            </note></para>
           <example>
             <title>Possible values for <userinput>uris</userinput></title>
             <para/>