doc/dev/developer_guide/essentials: update mailing lists

Update information for subscribing to Ceph development mailing lists as current documentation is outdated.

Fixes: https://tracker.ceph.com/issues/64580
Signed-off-by: Laimis Juzeliunas <[email protected]>

Author: laimis9133

doc/dev/developer_guide/essentials.rst

@@ -88,18 +88,20 @@ Ceph's Slack is https://ceph-storage.slack.com/.
 Mailing lists
 -------------
 
+Ceph developers and users discuss the project on `Ceph-related mailing lists`_.
+
+.. _`Ceph-related mailing lists`: https://ceph.com/en/community/connect
+
 Ceph Development Mailing List
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The ``[email protected]`` list is for discussion about the development of Ceph,
 its interoperability with other technology, and the operations of the
 project itself.
 
 The email discussion list for Ceph development is open to all. Subscribe by
-sending a message to ``[email protected]`` with the following line in the
-body of the message::
-
-    subscribe ceph-devel
+completing the `sign-up form on dev.ceph.io`_.
 
+.. _`sign-up form on dev.ceph.io`: https://lists.ceph.io/postorius/lists/dev.ceph.io
 
 Ceph Client Patch Review Mailing List
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -108,19 +110,10 @@ for the Linux kernel Ceph client component. Note that this list used to
 be an all-encompassing list for developers. When searching the archives, 
 remember that this list contains the generic devel-ceph archives before mid-2018.
 
-Subscribe to the list covering the Linux kernel Ceph client component by sending
-a message to ``[email protected]`` with the following line in the body
-of the message::
-
-    subscribe ceph-devel
-
-
-Other Ceph Mailing Lists
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-There are also `other Ceph-related mailing lists`_.
+Subscribe to the list covering the Linux kernel Ceph client component by using
+the `sub link for ceph-devel in vger.kernel.org`_.
 
-.. _`other Ceph-related mailing lists`: https://ceph.com/irc/
+.. _`sub link for ceph-devel in vger.kernel.org`: https://subspace.kernel.org/vger.kernel.org.html
 
 .. _irc: