Remove empty changelog sections (#3407)

* update changelog

* text update

* sample issue fix

* readme update

* changelogs update

* remove changelog empty sections

* spaces

* updates

* typo

* remove extra space

sdk/keyvault/azure-security-keyvault-certificates/CHANGELOG.md

@@ -2,15 +2,9 @@
 
 ## 4.0.0-beta.2 (2022-03-08)
 
-### Features Added
-
 ### Breaking Changes
 - Updated `CreateCertificateOperation.PollUntilDone()` (returned from `StartCreateCertificate()`)  to return the operation status instead of the newly created certificate.
 
-### Bugs Fixed
-
-### Other Changes
-
 ## 4.0.0-beta.1 (2021-11-09)
 
 ### New Features

sdk/keyvault/azure-security-keyvault-secrets/CHANGELOG.md

@@ -2,13 +2,8 @@
 
 ## 4.0.0-beta.2 (2022-03-08)
 
-### Features Added
-
-### Breaking Changes
-
-### Bugs Fixed
-
-### Other Changes
+- Second preview.
+  - Internal improvements. 
 
 ## 4.0.0-beta.1 (2021-09-08)