Update CHANGELOG.md
Add changes for 2.15.0
+## 2.15.0 (Feb, 3, 2022)
+
+FEATURES:
+
+* **New Resource:** `artifactory_virtual_rpm_repository` with support for `primary_keypair_ref` and `secondary_keypair_ref` and [GH-303]
+
+
## 2.14.0 (Feb, 3, 2022)
FEATURES:
