README.md: Minor typographical and grammar fixes
These are some minor fixes to the README.md files submitted by Aidan
Earle
[coverity]: https://scan.coverity.com/projects/mcuboot
[travis]: https://travis-ci.org/JuulLabs-OSS/mcuboot
-This is mcuboot, version 1.4.0
+This is mcuboot version 1.4.0
MCUboot is a secure bootloader for 32-bit MCUs. The goal of MCUboot is to
define a common infrastructure for the bootloader, system flash layout on
microcontroller systems, and to provide a secure bootloader that enables
-easy software upgrade.
+simple software upgrades.
MCUboot is operating system and hardware independent and relies on
-hardware porting layers from the operating system it works with. Currently,
-mcuboot works with both the Apache Mynewt, and Zephyr operating systems, but
-more ports are planned in the future. RIOT is currently supported as a boot
+hardware porting layers from the operating. Currently, mcuboot works
+with both the Apache Mynewt and Zephyr operating systems, but more
+ports are planned in the future. RIOT is currently supported as a boot
target with a complete port planned.
## Using MCUboot
