docs: Add note regarding arm64 testing using vfkit (#189)

### What does this PR do?

Adds note regarding applehv only running arm64 images.

### Screenshot / video of UI

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N/A

### What issues does this PR fix or reference?

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repository (or from another issue tracker). -->

References #184

### How to test this PR?

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Signed-off-by: Charlie Drage <charlie@charliedrage.com>

docs/vm_guide.md

@@ -12,6 +12,8 @@ However, we provide some detailed instructions on how to run this on different o
 
 The easiest solution to run this on macOS is by using [vfkit](https://github.com/crc-org/vfkit) which uses the native Apple hypervisor framework.
 
+NOTE: This will only run NATIVE architecture images. Your image must use the ARM64 output.
+
 ### Installation
 
 This can be installed via: