docs/CREDENTIALS: Don't write authorized_keys with executable bits

No reason to make this file executable.

(cherry picked from commit 47374e0)
(cherry picked from commit 30f9309)
(cherry picked from commit e09ef87)
(cherry picked from commit b28b9db)

Author: cgwalters

docs/CREDENTIALS.md

@@ -396,7 +396,7 @@ qemu-system-x86_64 \
         -drive if=none,id=hd,file=test.raw,format=raw \
         -device virtio-scsi-pci,id=scsi \
         -device scsi-hd,drive=hd,bootindex=1 \
-        -smbios type=11,value=io.systemd.credential.binary:tmpfiles.extra=$(echo "f~ /root/.ssh/authorized_keys 700 root root - $(ssh-add -L | base64 -w 0)" | base64 -w 0)
+        -smbios type=11,value=io.systemd.credential.binary:tmpfiles.extra=$(echo "f~ /root/.ssh/authorized_keys 600 root root - $(ssh-add -L | base64 -w 0)" | base64 -w 0)
 ```
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