doc/cephadm: rewrite part of adoption.rst

This PR adds a bit of explanatory text to the
section of the cephadm docs that explains how
to convert Ceph deployments that were not deployed
with cephadm to deployments that can be managed by
the cephadm command line tool.

diff --git a/doc/cephadm/adoption.rst b/doc/cephadm/adoption.rst
index 0a7db7313b8a050ddf2d81c163801e2c558d5569..45cae9efa038a8879e5d4c7fcdb7ce4f31f5dd2f 100644 (file)
--- a/doc/cephadm/adoption.rst
+++ b/doc/cephadm/adoption.rst
@@ -3,14 +3,19 @@
 Converting an existing cluster to cephadm
 =========================================
 
-Cephadm allows you to convert an existing Ceph cluster that
-has been deployed with ceph-deploy, ceph-ansible, DeepSea, or similar tools.
+It is possible to convert some existing clusters so that they can be managed
+with ``cephadm``. This statment applies to some clusters that were deployed
+with ``ceph-deploy``, ``ceph-ansible``, or ``DeepSea``.
+
+This section of the documentation explains how to determine whether your
+clusters can be converted to a state in which they can be managed by
+``cephadm`` and how to perform those conversions.
 
 Limitations
 -----------
 
-* Cephadm only works with BlueStore OSDs.  If there are FileStore OSDs
-  in your cluster you cannot manage them.
+* Cephadm works only with BlueStore OSDs. FileStore OSDs that are in your
+  cluster cannot be managed with ``cephadm``.
 
 Preparation
 -----------