Update changelog.txt

fix markup error

Author: ab9rf

docs/changelog.txt

@@ -78,7 +78,7 @@ Template for new versions:
 - `tweak`: ``drawbridge-tiles``: Make it so raised bridges render with different tiles in ASCII mode to make it more obvious that they ARE raised (and to indicate their direction)
 
 ## Fixes
-# ``Filesystem::as_string`` now always uses UTF-8 encoding rather than using the system locale encoding
+- ``Filesystem::as_string`` now always uses UTF-8 encoding rather than using the system locale encoding
 
 ## Misc Improvements