doc: Update "Getting Started" to link to start not install

Currently the "Getting Started" link points at the install page, not the "Intro to Ceph" section, which seems more appropriate.

If you're happy with this, can it get backported to the still-supported releases, please?

Signed-off-by: Matthew Vernon <[email protected]>

Author: mcv21

doc/index.rst

@@ -94,7 +94,7 @@ about Ceph, see our `Architecture`_ section.
 .. _Ceph Object Store: radosgw
 .. _Ceph Block Device: rbd
 .. _Ceph File System: cephfs
-.. _Getting Started: install
+.. _Getting Started: start
 .. _Architecture: architecture
 
 .. toctree::