Merge pull request #981 from ycaner06/patch-9

auth_db : more explanation for generic error

src/modules/auth_db/doc/auth_db_admin.xml

@@ -324,8 +324,9 @@ modparam("auth_db", "version_table", 0)
 		<para>Negative codes may be interpreted as follows:</para>
 		<itemizedlist>
 			<listitem><para>
-			<emphasis>-1 (generic error)</emphasis> - some generic error
-			occurred and no reply was sent out;
+			<emphasis>-1 (generic error)</emphasis> - Bad credentials ,
+			couldn't parse credentials , no memory left , couldn't fetch from table ,
+			couldn't get realm or some generic error occurred and no reply was sent out;
 			</para></listitem>
 			<listitem><para>
 			<emphasis>-2 (invalid password)</emphasis> - wrong password;