docs: remove redundant SWR/SPEC for Betterstack feature [PYSDK-127]

The user-facing contract was already covered by existing artefacts:
SWR-SYSTEM-GUI-HEALTH-1 authorises health visibility in the Launchpad
footer; SPEC_GUI_SERVICE FR-06 covers the embedded status indicator;
SPEC_PLATFORM_SERVICE FR-04 covers per-environment endpoint config,
and §7.2 covers URL validation. The per-environment Betterstack URL
resolution is a design refinement, not a new design input.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: olivermeyer