docs: Create release notes for 1.10.0 release

- Table of Contents

{:toc}

## Version 1.10.0

The 1.10.0 release of MCUboot contains...

### About this release

- Various fixes to boot serial.

- Various fixes to the mbed target.

- Various fixes to the Espressif native target.

- Various fixes to the Zephyr target.

- Workflow improvements with Zephyr CI.

- Add multi image support to the espressif esp32 target.

- Improvements and corrections to the simulator.

- Improve imgtool, including adding 3rd party signing support.

- Various fixes to the mynewt target.

- Various fixes to the nuttx target.

- Dates to dependencies for doc generation.

- Add downgrade prevention for modes using swap.

- Various general fixes to the boot code.

- Prefer swap move on zephyr if the scratch partition is not enabled.

- Upgrade fault-injection hardening, improving cases injections are detected.

- Add a new flash api `flash_area_get_sector`, along with support for each

  target, that replaces `flash_area_sector_from_off`. This is a step in cleaning

  up the flash API used by MCUboot.

### Security fixes

There are no security vulnerabilities reported on the MCUboot code for this

release. There have been several updates to the dependencies in the Ruby code

used to generate the documentation. This should only affect users that generate

their own documentation.

## Version 1.9.0

The 1.9.0 release of MCUboot contains various bug fixes, improves