ReleaseNotes.adoc: fix the "SDP and P4D Version Compatibility"
section, which was still listing 2025.2 as the latest release and
included P4D 2024.1 (past its End of Maintenance date). Now lists
2026.1 through 2024.2, matching the currently-supported P4D
release window. Doc-only Hot Fix, no tarball changes needed.