DOC: configuration.txt: fix typo in table_idle signature
An extra ',' was mistakenly added in table_idle converter signature
with commit ed36968 ("DOC: configuration.txt: add default_value for
table_idle signature").
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 98a85bd..161e740 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -17965,7 +17965,7 @@
period configured in the table. See also the sc_http_req_rate sample fetch
keyword.
-table_idle(<table>,[,<default_value>])
+table_idle(<table>[,<default_value>])
Uses the input sample to perform a look up in the specified table. If the key
is not found in the table, the converter fails except if <default_value> is
set: this makes the converter succeed and return <default_value>. If the key