docs: allow toolchain rebuild on full rebuild

rebased on Azure Linux 20260304 is causing toolchain to rebuild during
build-packages on full build, this is expected hence set flag to allow
it.

Signed-off-by: Lee Chee Yang <chee.yang.lee@intel.com>

Author: cheeyanglee

docs/developer-guide/get-started/emt-build-and-deploy.md

@@ -177,7 +177,7 @@ For example, to build a RAW image without real-time extensions, use `edge-image.
 
    ```bash
    # Rebuild packages/RPMs local toolchain
-   sudo make build-packages REBUILD_TOOLS=y VALIDATE_TOOLCHAIN_GPG=n
+   sudo make build-packages REBUILD_TOOLS=y VALIDATE_TOOLCHAIN_GPG=n ALLOW_TOOLCHAIN_REBUILDS=y
    ```
 
 8. Build the toolkit image:

docs/developer-guide/get-started/emt-building-howto.md

@@ -73,7 +73,7 @@ git clone https://github.com/open-edge-platform/edge-microvisor-toolkit --branch
 
    ```bash
    # Rebuild packages/RPMs
-   sudo make build-packages REBUILD_TOOLS=y VALIDATE_TOOLCHAIN_GPG=n
+   sudo make build-packages REBUILD_TOOLS=y VALIDATE_TOOLCHAIN_GPG=n ALLOW_TOOLCHAIN_REBUILDS=y
    ```
 
 ## Build the Edge Microvisor Toolkit Image