changelog: Fix whitespace in `Changelog` header

0ee776642275 ("platform: Add alias members to PDRRepoChgEvent") added
some entries to the changelog, but managed to ding the top level header
whitespace in the process. Undo that.

Fixes: 0ee776642275 ("platform: Add alias members to PDRRepoChgEvent")
Change-Id: Ie2e769e0d97d0ed2601933740ded5f145cf40542
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d42e4ea..bea48b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-#Changelog
+# Changelog
 
 All notable changes to this project will be documented in this file.