chore(docs): update of OEL changelog (#2532)

Author: ory-bot

docs/self-hosted/oel/oauth2/changelog/v26.2.7.md

@@ -1 +1,10 @@
-No changelog entries found for hydra/oel in versions v26.2.7
+## v26.2.7
+
+### New indexes on Hydra OAuth 2.0 token tables
+
+Hydra adds `(nid, subject, client_id)` indexes to `hydra_oauth2_access` and `hydra_oauth2_refresh`. The indexes are created online
+on CockroachDB and PostgreSQL, so applying the upgrade does not block reads or writes against the token tables during the schema
+change.
+
+On Hydra OEL and Hydra Cloud, the new indexes accelerate consent session revocation, complementing recent code-level improvements
+to the OEL revoke flow.