Firecracker release v0.12.0

* updated version in TOML files and API spec
* ran `cargo update`
* adjusted CHANGELOG.MD
* enforced functional version on backtrace crate

Signed-off-by: Diana Popa <dpopa@amazon.com>

CHANGELOG.md

@@ -1,22 +1,32 @@
 # Changelog
 
-##  [Unreleased]
+## [0.12.0]
 
 ### Added
 - The `/logger` API has a new field called `options`. This is an array of
   strings that specify additional logging configurations. The only supported
   value is `LogDirtyPages`.
 - When the `LogDirtyPages` option is configured via `PUT /logger`, a new metric
   called `memory.dirty_pages` is computed as the number of pages dirtied by the
-  guest since the last time the metric was flushed. 
+  guest since the last time the metric was flushed.
+- Log messages on both graceful and forceful termination.
+- Availability of the list of dependencies for each commit inside the code base.
+- Documentation on vsock experimental feature and host setup recommendations.
 
 ### Changed
 
 - `PUT` requests on `/mmds` always return 204 on success.
 - `PUT` operations on `/network-interfaces` API resources no longer accept 
   the previously required `state` parameter.
 - The jailer starts with `--seccomp-level=2` (was previously 0) by default.
-- Log messages use `anonymous-instance` as instance-id if no instance-id is set.
+- Log messages use `anonymous-instance` as instance id if none is specified.
+
+### Fixed
+- Fixed crash upon instance start on hosts without 1GB huge page support.
+- Fixed "fault_message" inconsistency between Open API specification and code base.
+- Ensure MMDS compatibility with C5's IMDS implementation.
+- Corrected the swagger specification to ensure `OpenAPI 2.0` compatibility.
+
 
 ## [0.11.0]