Update CHANGES

CHANGES

@@ -16,13 +16,16 @@ are not marked).
 * Shorten conflict messages even more
 * Added `opam admin add-constraint` to amend a set of reverse dependencies in a
   repository
-* New format for `depexts:`, easier to understand and more flexible
+* New format for `depexts:`, easier to understand and more flexible. Depexts for
+  the host can now be inferred by opam
 * Optimised search criteria for the built-in solver
 * Added a `build-id` variable to identify package builds
 * Extend hooks (new variable `installed-files`, new session hooks)
 * `opam switch create DIR` now installs packages defined in `DIR`
 * Added system-related variables `arch`, `os`, `os-distribution`, `os-family`,
   `os-version`
+* Added support for using `opam.locked` files instead of `opam` ones (`--locked`)
+* Opam plugins are now made available across switches
 
 2.0.0~beta4
 * Building with OCaml < 4.02.3 is no longer supported