docs: add v2.1.1 release notes (#5342) (#5344)

(cherry picked from commit d9cc2e5)

Co-authored-by: pyroscope-development-app[bot] <191832211+pyroscope-development-app[bot]@users.noreply.github.com>
Co-authored-by: Aleksandar Petrov <8142643+aleks-p@users.noreply.github.com>

Author: pyroscope-development-app[bot]

docs/sources/release-notes/v2-1.md

@@ -5,6 +5,11 @@ description: Release notes for Grafana Pyroscope 2.1
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+## Version 2.1.1 release notes
+
+### Security fixes
+* Update Go toolchain to 1.25.12, addressing CVE-2026-42505 and CVE-2026-39822 (security) ([#5338](https://github.com/grafana/pyroscope/pull/5338))
+
 ## Version 2.1.0 release notes
 
 The Pyroscope team is excited to present Grafana Pyroscope 2.1.0.