[Cosmetic] Remove Peter Drucker's quote "If you can't measure it, you can't improve it."

[bertysentry]

Note I plan on submitting more meaningful change proposals, but this one stroke me first when reading the specification.

In Software_Carbon_Intensity_Specification.md, we need to remove the introductory quote from Peter Drucker.

Peter Drucker actually never said "If you can't measure it, you can't improve it.". See https://www.drucker.institute/thedx/measurement-myopia for more information.

[buchananwp]

As much as I like this misattributed quote, quotes should likely not live within a specification. I think I played some small part in its initial inclusion, but agree with this

[seanmcilroy29]

See #350