Add unsupported riscv64 architecture (#7859)

This PR makes it easy for users to build a Debian container images which
is able to run on a riscv64 architecture using a Debian Container, or if
needed, you can extract the binary from this container, but the user
needs to be sure the libraries are available and supported if using
Docker is not an option.

Signed-off-by: BlackDex <black.dex@gmail.com>

docker/README.md

@@ -15,6 +15,7 @@ Some unsupported platforms for Debian based images. These are not built and test
 - 386     (linux/386)
 - ppc64le (linux/ppc64le)
 - s390x   (linux/s390x)
+- riscv64 (linux/riscv64)
 
 To build these containers you need to enable QEMU binfmt support to be able to run/emulate architectures which are different then your host.<br>
 This ensures the container build process can run binaries from other architectures.<br>

docker/docker-bake.hcl

@@ -148,6 +148,12 @@ target "debian-s390x" {
   platforms = ["linux/s390x"]
   tags = generate_tags("", "-s390x")
 }
+
+target "debian-riscv64" {
+  inherits = ["debian"]
+  platforms = ["linux/riscv64"]
+  tags = generate_tags("", "-riscv64")
+}
 // ==== End of unsupported Debian architecture targets ===
 
 // A Group to build all platforms individually for local testing