Add CHANGELOG entry

Pratyush · Pratyush · commit b065a65e06fe · 2021-04-22T16:22:30.000-07:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## Pending
+### Breaking changes
+- [\#348](https://github.com/arkworks-rs/snark/pull/334) Introduce a `Relation` trait, change the `SNARK` traits to use it, and break down `ConstraintSynthesizer` into three traits.
+
 ## v0.2.0
 
 ### Breaking changes
