There is a discrepancy in the docs for the default projections setting. This line specifying the default setting:

https://github.com/spack/spack/blob/develop/lib/spack/docs/config_yaml.rst?plain=1#L41

{architecture}/{compiler.name}-{compiler.version}/{name}-{version}-{hash}

compared to the setting in the default config.yaml:

https://github.com/spack/spack/blob/develop/etc/spack/defaults/base/config.yaml#L22

{architecture.platform}-{architecture.target}/{name}-{version}-{hash}

I assume that line in the docs was overlooked and should be replaced with the setting found in the default config.yaml.