Fix `actionview/CHANGELOG.md`

- Add missing dots at the end of sentences.
- Wrap RecordTagHelper into `.
- `RecordTagHelper` => `ActionView::Helpers::RecordTagHelper`.

[ci skip]

actionview/CHANGELOG.md

-*   Remove RecordTagHelper
+*   Remove `ActionView::Helpers::RecordTagHelper`.
 
     *Yoshiyuki Hirano*
 
-*   Disable `ActionView::Template` finalizers in test environment
+*   Disable `ActionView::Template` finalizers in test environment.
 
     Template finalization can be expensive in large view test suites.
     Add a configuration option,