modify changelog.md file add datasource setting

Author: hhermanwang

CHANGELOG.md

@@ -13,6 +13,9 @@ ENHANCEMENTS:
 * Resource `tencentcloud_cdn_domain` add `range_origin_switch` to support range back to source configuration.
 * Resource `tencentcloud_cdn_domain` add `rule_cache` to support advanced path cache configuration.
 * Resource `tencentcloud_cdn_domain` add `request_header` to support request header configuration.
+* Data Source `tencentcloud_cdn_domains` add `range_origin_switch` to support range back to source configuration.
+* Data Source `tencentcloud_cdn_domains` add `rule_cache` to support advanced path cache configuration.
+* Data Source `tencentcloud_cdn_domains` add `request_header` to support request header configuration.
 
 ## 1.51.1 (December 22, 2020)