Minor refactor, update changelog

CHANGELOG.md

@@ -1,3 +1,5 @@
+- Move edge cases to external csv `edge_cases.csv`
+---
 - Fix some incorrectly escaped edge cases
 - Updated descriptor for new pipeline
 ___

dataset.yaml

@@ -220,9 +220,9 @@ _steps:
   - step: &edge_cases
       type: ExactReplace
       description: "Remove a few edge cases."
-      pack: [ 'edge_cases.csv' ]
+      pack: [ 'pack/edge_cases.csv' ]
       config:
-        packedReplacements: [ 'edge_cases.csv' ]
+        packedReplacements: [ 'pack/edge_cases.csv' ]
 
 _passes:
   - pass: &usernames