Add a changelog for the 1.0.0 release

This includes the changes from the various subprojects since their last
release.

Signed-off-by: Jeremy Cline <jeremy@jcline.org>

CHANGELOG.rst

@@ -1,8 +1,26 @@
 1.0.0
 =====
 
-* Merge the fmn.lib, fmn.consumer, and fmn.rules repositories. For changelogs
-  of those projects prior to this merge, consult the following repositories:
-    - https://github.com/fedora-infra/fmn.consumer/
-    - https://github.com/fedora-infra/fmn.lib/
-    - https://github.com/fedora-infra/fmn.rules/
+* Documentation is now available `online <https://fmn.readthedocs.io/>`_.
+
+* Merge the fmn.lib, fmn.consumer, and fmn.rules repositories. The changelogs
+  for those projects since the last release of each is included below.
+  - https://github.com/fedora-infra/fmn.lib/
+  - https://github.com/fedora-infra/fmn.rules/
+
+* The FMN consumer now requeues messages it failed to send with the IRC backend
+  (https://github.com/fedora-infra/fmn.consumer/pull/96).
+
+* There is now a Server-Sent Events backend for the FMN consumer
+  (https://github.com/fedora-infra/fmn.consumer/pull/92 and
+  https://github.com/fedora-infra/fmn.lib/pull/62).
+
+* Emails are now split up into 20MB chunks if necessary
+  (https://github.com/fedora-infra/fmn.consumer/pull/88).
+
+* The digest producer is now run in a separate process
+  (https://github.com/fedora-infra/fmn.consumer/pull/86).
+
+* The API for ``handle_batch`` in the consumer has changed to accept a list
+  of message dictionaries rather than ``QueuedMessage`` objects
+  (https://github.com/fedora-infra/fmn.consumer/pull/86)