docs(CHANGES): Note new subprocess command

Author: tony

CHANGES

@@ -13,6 +13,12 @@ $ pip install --user --upgrade --pre libvcs
 
 - _Add your latest changes from PRs here_
 
+### Development
+
+- {issue}`#336`: {class}`~libvcs.utils.subprocess.SubprocessCommand`: Encapsulated {mod}`subprocess`
+  call in a {func}`dataclasses.dataclass` for introspecting, modifying, mocking and controlling
+  execution.
+
 ## libvcs 0.12.0, "Nimbus" (2022-04-24)
 
 ### Breaking