Prepare changelog for release

Author: Leonidas-from-XIV

CHANGES.md

@@ -1,4 +1,4 @@
-### unreleased
+### 2.2.0
 
 #### Added
 
@@ -8,8 +8,6 @@
 
 - Preserve indentation in multiline OCaml blocks in .mli files (#395, @panglesd)
 
-#### Deprecated
-
 #### Fixed
 
 - Fixed compatibility with Cmdliner 1.1.0 (#371, @Leonidas-from-XIV)
@@ -29,8 +27,6 @@
   automatic insertion of semicolons in the corrected files introduced in MDX
   2.0.0. (#398, @Leonidas-from-XIV)
 
-#### Security
-
 ### 2.1.0
 
 #### Added