Move perennials release note to Upcoming Release section

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: BertoGBG

docs/release_notes.rst

@@ -15,6 +15,8 @@ Upcoming Release
 ..   The features listed below are not released yet, but will be part of the next release! 
 ..   To use the features already you have to use the ``master`` branch.
 
+* Adding `perennials gbr` for production of perennial crops instead of 1st generation biofuels, followed by Green Bio Refining to proteins and biogas. (https://github.com/PyPSA/technology-data/pull/255)
+
 `v0.15.0 <https://github.com/PyPSA/technology-data/releases/tag/v0.15.0>`__ (9th June 2026)
 ================================================================================================
 
@@ -36,7 +38,6 @@ Upcoming Release
 
 `v0.14.0 <https://github.com/PyPSA/technology-data/releases/tag/v0.14.0>`__ (13th February 2026)
 ================================================================================================
-* Adding `perennials gbr` for production of perennial crops instead of 1st generation biofuels, followed by Green Bio Refining to proteins and biogas.
 
 * Changed currency year from 2020 to 2025 for all cost assumptions using updated Eurostat inflation rates. (https://github.com/PyPSA/technology-data/pull/263)