Update CHANGELOG.md with details from pull request #763

Obvious fix; these changes are the result of automation not creative thinking.

CHANGELOG.md

@@ -1,14 +1,15 @@
-<!-- latest_release 3.12.8 -->
-## [v3.12.8](https://github.com/inspec/train/tree/v3.12.8) (2024-08-30)
+<!-- latest_release unreleased -->
+## Unreleased
 
 #### Merged Pull Requests
-- Update chefstyle requirement from 2.1.1 to 2.2.3 [#756](https://github.com/inspec/train/pull/756) ([dependabot[bot]](https://github.com/dependabot[bot]))
+- update docs with examples to set valid platform family [#763](https://github.com/inspec/train/pull/763) ([sathish-progress](https://github.com/sathish-progress))
 <!-- latest_release -->
 
 <!-- release_rollup since=3.12.7 -->
 ### Changes not yet released to rubygems.org
 
 #### Merged Pull Requests
+- update docs with examples to set valid platform family [#763](https://github.com/inspec/train/pull/763) ([sathish-progress](https://github.com/sathish-progress)) <!-- 3.12.8 -->
 - Update chefstyle requirement from 2.1.1 to 2.2.3 [#756](https://github.com/inspec/train/pull/756) ([dependabot[bot]](https://github.com/dependabot[bot])) <!-- 3.12.8 -->
 <!-- release_rollup -->