Document that Instant may or may not include system-suspend time

[the8472]

Since people are still occasionally surprised by this let's make it more explicit. This doesn't add any new guarantees, only documents the status quo.

Related issues: #87906#79462

[rustbot]

r? @Mark-Simulacrum

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[Mark-Simulacrum]

@bors r+

[bors]

📌 Commit b0412d5 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit b0412d5 with merge 2f89c41...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 2f89c41 to master...

[rust-timer]

Finished benchmarking commit (2f89c41): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.3%	[3.3%, 3.3%]	1
Regressions ❌ (secondary)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.3%	[3.3%, 3.3%]	1

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 631.709s -> 630.4s (-0.21%)
Artifact size: 317.40 MiB -> 317.38 MiB (-0.00%)