formate hyperlink of Fluentd in README.rst.

correspondence with other hyperlinks.

Change-Id: Ifaeb2c834577c3583d7f7368039073abccdbbef9

README.rst

@@ -93,7 +93,7 @@ Kolla-Ansible deploys containers for the following infrastructure components:
 - `Elasticsearch <https://www.elastic.co/de/products/elasticsearch>`__ and
    `Kibana <https://www.elastic.co/de/products/kibana>`__ to search, analyze,
    and visualize log messages.
-- `Fluentd <https://http://www.fluentd.org/>__` as an open source data collector
+- `Fluentd <https://http://www.fluentd.org/>`__ as an open source data collector
   for unified logging layer.
 - `HAProxy <http://www.haproxy.org/>`__ and
   `Keepalived <http://www.keepalived.org/>`__ for high availability of services