release-notes: Document that its possible to install with systemd-boot

Place a release note for the next verison of anaconda which notes that
it is now possible given the right set of packages/etc to install
a system utilizing systemd-boot.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>

docs/release-notes/systemd-boot.rst

@@ -0,0 +1,20 @@
+:Type: Kickstart Installation
+:Summary: Install an image using systemd-boot rather than grub (#2135531)
+
+:Description:
+    With this release, systemd-boot can be selected as an alternative boot
+    loader for testing and development purposes.
+
+    This can be done with 'inst.sdboot' from the grub/kernel command
+    line or with '--sdboot' in a kickstart file as part of the
+    bootloader command.  The resulting machine should be free of grub,
+    shim, and grubby packages, with all the boot files on the EFI
+    System Partition (ESP). This may mean that it is wise to dedicate
+    the space previously allocated for /boot to the ESP in order to
+    assure that future kernel upgrades will have sufficient space.
+
+    For more information, refer to the anaconda and systemd-boot documentation.
+
+:Links:
+    - https://bugzilla.redhat.com/show_bug.cgi?id=2135531
+    - https://github.com/rhinstaller/anaconda/pull/4368