update changelog identity beta (#15995)

sdk/identity/azure-identity/CHANGELOG.md

@@ -1,6 +1,18 @@
 # Release History
 
-## 1.2.0-beta.2 (Unreleased)
+## 1.2.0-beta.2 (2020-10-06)
+
+### New Features
+- Added the methods `pfxCertificate(InputStream certificate, String clientCertificatePassword)` and `pemCertificate(InputStream certificate)` in `ClientCertificateCredentialBuilder`.
+- Added `includeX5c(boolean)` method in `ClientCertificateCredentialBuilder` to enable subject name / issuer based authentication.
+- Added a default `challengeConsumer` in `DeviceCodeCredentialBuilder` which prints the device code information to console. The `challengeConsumer` configuration is no longer required in `DeviceCodeCredentialBuilder`.
+
+### Dependency Updates
+- Upgraded `azure-core` dependency to 1.9.0
+- Upgraded `jna-platform` dependency to 5.6.0
+- Upgraded `msal4j` dependency to 1.7.1
+
+
 
 
 ## 1.2.0-beta.1 (2020-09-11)