doc/start: explain "OSD"

Explain the initialism "OSD" and link to its definition in the glossary.
This PR is raised in response to an anonymous documentation bug that reads

  "Paragraph 2 uses the acronym OSD without any explanation.
   This makes it very difficult to understand this part of
   the documentation as there is no indication of what this
   acronym is until much further into the documentation. Replace
   first occurence of OSD with Object Storage Daemon (OSD) or
   link it to the glossary."
     -- https://pad.ceph.com/p/Report_Documentation_Bugs

Co-authored-by: Anthony D'Atri <anthony.datri@gmail.com>
Signed-off-by: Zac Dover <zac.dover@proton.me>
(cherry picked from commit a78fe85470c2471574aceb723cd304498cde1afb)

diff --git a/doc/start/intro.rst b/doc/start/intro.rst
index 3a50a8733676e27a828d7d90d29c22c5957e62b6..9881a7205487c48fb5ceb6f928067b6bd6a1c781 100644 (file)
--- a/doc/start/intro.rst
+++ b/doc/start/intro.rst
@@ -9,10 +9,10 @@ System`.  All :term:`Ceph Storage Cluster` deployments begin with setting up
 each :term:`Ceph Node` and then setting up the network. 
 
 A Ceph Storage Cluster requires the following: at least one Ceph Monitor and at
-least one Ceph Manager, and at least as many Ceph OSDs as there are copies of
-an object stored on the Ceph cluster (for example, if three copies of a given
-object are stored on the Ceph cluster, then at least three OSDs must exist in
-that Ceph cluster). 
+least one Ceph Manager, and at least as many :term:`Ceph Object Storage
+Daemon<Ceph OSD>`\s (OSDs) as there are copies of a given object stored in the
+Ceph cluster (for example, if three copies of a given object are stored in the
+Ceph cluster, then at least three OSDs must exist in that Ceph cluster).
 
 The Ceph Metadata Server is necessary to run Ceph File System clients.