docs: cross-reference hosted CPU capping from APP_ISOLATION.md

[onel]

What

Adds a one-line cross-reference note to docs/specs/APP_ISOLATION.md in the "Resource limits" section, pointing to ENVIRONMENT.md # Per-instance resource limits for the hosted profile's CPU capping behavior.

Why

PR #228 updated ENVIRONMENT.md to describe the per-instance cgroup limit mechanism: memory is capped in both profiles; CPU is capped only in hosted. The APP_ISOLATION.md "Resource limits" section correctly states CPU is never capped — true for the appliance profile — but does not cross-reference back to ENVIRONMENT.md for the hosted exception. A reader of APP_ISOLATION.md alone would not know that hosted caps CPU.

ENVIRONMENT.md already cross-references APP_ISOLATION.md # Resource limits; this adds the reverse pointer.

[greptile-apps]

Confidence Score: 5/5

Safe to merge — a single prose sentence added to a documentation file with no code changes.

The change is a two-line blockquote added to a docs file. The cross-reference target exists at the exact heading named, the stated fact (CPU is capped in hosted) is confirmed by the referenced section, and the style matches the repo's existing cross-reference convention.

No files require special attention.

Important Files Changed

Filename	Overview
docs/specs/APP_ISOLATION.md	Adds a blockquote cross-reference note after the "CPU is never capped" paragraph, pointing readers to ENVIRONMENT.md # Per-instance resource limits for the hosted-profile exception. The target section exists and the factual claim is correct.

_{Reviews (1): Last reviewed commit: "docs: cross-reference hosted CPU capping..." | Re-trigger Greptile}