DOC: configuration: add missing index entries for tune.pool-{low,high}-fd-ratio

These two keywords didn't have an entry in the index. They were added in
2.0 by commit 88698d966 ("MEDIUM: connections: Add a way to control the
number of idling connections.") so this must be backported to 2.0.

(cherry picked from commit a8e2d9790548f395c5f3782117ef2eef350c7c39)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 2f20960904eb35b36baf4e2d279f1344743f50e8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
1 file changed