.ostc-ci,docs: add build job for Raspberry Pi 4

Raspberry Pi 4 was added a while ago but is not a part of CI.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>

.ostc-ci/machines-and-flavours.yaml

@@ -67,6 +67,11 @@ linux-stm32mp1-av96:
   variables:
     MACHINE: stm32mp1-av96
 
+linux-raspberrypi4-64:
+  extends: .build-linux
+  variables:
+    MACHINE: raspberrypi4-64
+
 zephyr-qemu-x86:
   extends: .build-zephyr
   variables:

docs/ci/machines-and-flavours.rst

@@ -93,6 +93,19 @@ architecture.
 The cache for this job is not public, pending legal review of any firmware that
 may be included.
 
+linux-raspberrypi4-64
+.....................
+
+This job extends `.build-linux` job from the manifest repository and builds
+``allscenarios-image-base-tests`` and ``allscenarios-image-extra-tests`` using
+the Linux flavour of All Scenarios OS and ``MACHINE=raspberrypi4-64``. This job
+checks that All Scenarios OS software can be built for the Raspberry Pi 4B
+development board, which contains the BCM2711 SoC, which implements 64bit ARMv8
+architecture.
+
+The cache for this job is not public, pending legal review of any firmware that
+may be included.
+
 zephyr-qemu-x86
 ...............