Add overlay-offset var + docs

[langermank]

Adds a size var to be used by overlays like Tooltip, ActionMenu etc that are anchored to a trigger.

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🦋 Changeset detected

Latest commit: 327e2c7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/primitives	Patch

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Design Token Diff

/css/functional/size/size.css

+++ /home/runner/work/primitives/primitives/tokens-next-private/css/functional/size/size.css	2024-02-13 21:43:01.232752508 +0000
@@ -70,4 +70,5 @@
 --overlay-paddingBlock-condensed: 0.25rem;
 --overlay-paddingBlock-normal: 0.75rem;
 --overlay-borderRadius: 0.375rem;
+  --overlay-offset: 0.25rem;
}