doc/rados: add link to pg blog post

Add a link in the "Placement Groups" section that links to Sage Weil's
April 5, 2019 blog post "New in Nautilus: PG merging and autotuning".

Signed-off-by: Zac Dover <zac.dover@proton.me>

diff --git a/doc/rados/operations/placement-groups.rst b/doc/rados/operations/placement-groups.rst
index fb21863bb09837b795e32de3b514c1930f19d78a..2e2e385a5161b6feca4b6d25ad831c60ae26aa79 100644 (file)
--- a/doc/rados/operations/placement-groups.rst
+++ b/doc/rados/operations/placement-groups.rst
@@ -4,6 +4,11 @@
  Placement Groups
 ==================
 
+See Sage Weil's blog post `New in Nautilus: PG merging and autotuning
+<https://ceph.io/en/news/blog/2019/new-in-nautilus-pg-merging-and-autotuning/>`_
+for information about the relationship of placement groups to pools and to
+objects.
+
 .. _pg-autoscaler:
 
 Autoscaling placement groups