Add release note

Author: tgilon

docs/release_notes.rst

@@ -28,6 +28,8 @@ Upcoming Release
 
 * Updates the documentation with compile_cost_assumptions_usa.py (https://github.com/PyPSA/technology-data/pull/186)
 
+* Add `purge` and `all` rules to clean all generated outputs and regenerate them (https://github.com/PyPSA/technology-data/pull/187)
+
 `v0.11.0 <https://github.com/PyPSA/technology-data/releases/tag/v0.11.0>`__ (24th January 2025)
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