Updated revnumber and revdate fields in adoc files for release (release process Step 11, major releases only).
All 15 .adoc files under doc/ and Unsupported/doc/ bumped to v2026.1,
2026-09-03. SDP_DeveloperGuide.adoc was on a stale v2025.1 (had missed at
least one prior release cycle); now consistent with everything else.
Agent: Claude Code, Model: Claude Sonnet 5 (claude-sonnet-5), operating as bot_Claude_Anthropic.