docs: Document supported targets

Move supported architecture and backend guidance from AGENTS.md into
README.md and CONTRIBUTING.md.

On-behalf-of: SAP philipp.schuster@sap.com
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>

AGENTS.md

@@ -11,9 +11,6 @@ reviewable, and compatible with the project's normal engineering constraints.
 - Start with `README.md` for the project shape and `CONTRIBUTING.md` for the
   contribution rules, coding style, commit message guidance, and LLM assistance
   disclosure policy. Following `CONTRIBUTING.md` is crucial!
-- The main supported architectures are `x86_64` and `aarch64`; the main
-  hypervisor backends are KVM and MSHV. `x86_64` with KVM gets the most regular
-  exercise, but changes must not make the other first-class targets worse.
 
 ### Change Guidelines
 
@@ -78,4 +75,3 @@ reviewable, and compatible with the project's normal engineering constraints.
 - Temporary allowances such as `#[allow(unused)]` or ignored tests are only
   acceptable if resolved within the same commit series or paired with a clear
   TODO referencing a ticket. Ask the developer if in doubt.
-

CONTRIBUTING.md

@@ -11,6 +11,11 @@ license of those projects.
 New code should be under the [Apache v2
 License](https://opensource.org/licenses/Apache-2.0).
 
+Cloud Hypervisor's main supported architectures are `x86_64` and `aarch64`,
+and the main hypervisor backends are KVM and MSHV. `x86_64` with KVM gets the
+most regular exercise, but changes should not make the other supported
+architecture and backend combinations worse.
+
 ## Coding Style & Code Comments
 
 We use the [Rust Style] guide and enforce formatting and linting in CI,

README.md

@@ -59,10 +59,10 @@ based on the [Rust VMM](https://github.com/rust-vmm) crates.
 
 ### Architectures
 
-Cloud Hypervisor supports the `x86-64`, `AArch64` and `riscv64`
-architectures, with functionality varying across these platforms. The
-functionality differences between `x86-64` and `AArch64` are documented
-in [#1125](https://github.com/cloud-hypervisor/cloud-hypervisor/issues/1125).
+Cloud Hypervisor's main supported architectures are `x86-64` and `AArch64`,
+with functionality varying across these platforms. The functionality
+differences between `x86-64` and `AArch64` are documented in
+[#1125](https://github.com/cloud-hypervisor/cloud-hypervisor/issues/1125).
 The `riscv64` architecture support is experimental and offers limited
 functionality. For more details and instructions, please refer to [riscv
 documentation](docs/riscv.md).