Update Changelog.md (#9235)

Summary:
Broken formatting

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Pull Request resolved: #9235

Reviewed By: pieterv

Differential Revision: D66648860

fbshipit-source-id: ef0e631b051204832b0680d01421d0cdc48c2d8d

Changelog.md

@@ -9,6 +9,7 @@ Library Definitions:
 type ReactConfigShim<Props, DefaultProps> = $ReadOnly<{
   ...Omit<Props, $Keys<DefaultProps>>, ...Partial<DefaultProps>
 }>;
+```
 
 ### 0.254.2