docs: stop presenting Threadripper 68+68=137 W as a correct RAPL sum

[Dmao233]

Description

docs/explanation/rapl.md showed the Threadripper 1950X teaser

package-0-die-0: 68 W | package-0-die-1: 68 W | CodeCarbon: 137 W

with no note that those two dies can report the same socket-wide RAPL counter. That line was easy to read as confirmed-correct behaviour. It is the double-count discussed in #1274 / #1276 / #1379: one meter read twice, so the CPU RAPL value is ~68 W, not 137 W.

This PR only annotates the docs. It does not implement Linux RAPL deduplication (that remains #1276).

Changes in docs/explanation/rapl.md:

• Mark the 68 W + 68 W = 137 W teaser as the known over-count.
• Note mirrored per-die packages next to the existing hierarchy double-count explanation.
• Qualify the AMD bullets that told readers to sum every package-X-die-Y domain.
• Distinguish the later Threadripper capture, which exposes a single package-0 (kernel-dependent).

Related Issue

Fixes #1392

Related: #1274, #1276, #1379

Motivation and Context

Readers were being taught that summing two identical 68 W die readings is the right RAPL result. Whatever lands in #1276, that example should not stay unannotated.

How Has This Been Tested?

• Confirmed no open complete PR already targets docs: rapl.md presents the Threadripper 68+68 = 137 W sum as correct #1392.
• Built the docs: uv run --only-group doc task docs — no issues found, link check passed.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

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Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the docs/how-to/contributing.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.