Update platform.md

Co-authored-by: Natalie Arellano <narellano@vmware.com>
Signed-off-by: Ralf Pannemans <ralf.pannemans@googlemail.com>

platform.md

@@ -949,8 +949,8 @@ The launcher:
 
 Given stack metadata containing `run-image.image` and a set of `run-image.mirrors`. The `<run-image>` for a given `<image>` shall be resolved as follows:
 - **If** any of `run-image.image` or `run-image.mirrors` has a registry matching that of `<image>`, this value will become the `<run-image>`
-- **If** the `run-image.image` is accessible with read permissions, this value will become the `<run-image>`
-- The first value from the `run-image.mirrors` accessible with read permissions will become the `<run-image>`
+**If** any of `run-image.image` or `run-image.mirrors` is accessible with read permissions and has a registry matching that of `<image>`, this value will become the `<run-image>`
+**If** none of `run-image.image` or `run-image.mirrors` has a registry matching that of `<image>`, the first value of `<run-image.image>` or `run-image.mirrors` that is accessible with read permissions will become the `<run-image>`
 
 ### Registry Authentication