Update changelog

CHANGELOG.md

@@ -1,5 +1,14 @@
 ## Unreleased
 
+- Move to 'prettyprinter` library for pretty printing.
+
+  This is a potentially breaking change when one uses the '*Doc' family of functions
+  (like `headerDoc`) from `Options.Applicative`. However, as versions of
+  'ansi-wl-pprint > 1.0' export a compatible `Doc` type, this can be mitigated.
+
+  One can also either import directly from `Options.Applicative.Help` or from the
+  `Prettyprinter` module of 'prettyprinter'.
+
 - Export `helpIndent` from `Options.Applicative`.
 
 - Export completion script generators from `Options.Applicative.BashCompletion`.
@@ -15,6 +24,8 @@
 
 - Improve documentation.
 
+- Drop support for GHC 7.0 and 7.2.
+
 ## Version 0.17.0.0 (1 Feb 2022)
 
 - Make tabulation width configurable in usage texts.