Copy edit README.md

Copy edit for active voice, branding, spelling and other minor grammar fixes.

Author: Amanda Butler

targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/README.md

@@ -1,21 +1,21 @@
 # Cortex-M3 Design Start Eval package example on MPS2+ board
 
-This folder includes the port of mbed OS on the example system of the Cortex-M3
+This folder includes the port of Mbed OS on the example system of the Cortex-M3
 Design Start Eval package. This example is implemented in FPGA on the MPS2+
-board. Please check the [Mbed page](https://os.mbed.com/platforms/ARM-CM3DS/) of
-this target for more information.
+board. Please see this target's [Mbed page](https://os.mbed.com/platforms/ARM-CM3DS/)
+for more information.
 For convenience, this target is called **CM3DS**.
 
 ## Compiling
 
-The target name is `ARM_CM3DS_MPS2`, you should be able to compile Mbed OS
+The target name is `ARM_CM3DS_MPS2`. You can compile Mbed OS
 projects for CM3DS with:
 
 ```bash
 mbed compile -t COMPILER -m ARM_CM3DS_MPS2
 ```
 
-The following compilers are supported (replace `COMPILER` with):
+Mbed OS supports the following compilers (replace `COMPILER` with):
 
 * `ARM` for Arm Compiler version 5.
 * `GCC_ARM` for GNU Compiler for Arm.
@@ -25,9 +25,9 @@ The following compilers are supported (replace `COMPILER` with):
 
 Because of the new memory configuration introduced in commit `CM3DS: switch to
 larger memories for code and data`, it
-has become easier (and portable amoung all compilers) to use `.elf` files
-instead of `.bin`. `.elf` files are now the default for CM3DS projects and only
-they will be generated from the compilation.
+has become easier (and portable among all compilers) to use `.elf` files
+instead of `.bin`. `.elf` files are now the default for CM3DS projects, and compilation
+generates only them.
 For `.elf` files to work, you need **at least version 2.2.5** of the MPS2+
 firmware. For more information, please see the [firmware version 2.2.6 and instructions on how to put it
 in the MPS2+ board](https://community.arm.com/processors/designstart/f/discussions/9727/mps2-firmware-for-mbed).
@@ -40,23 +40,26 @@ If you want to execute the Mbed OS greentea tests on CM3DS, you need
 * `mbedls` does not automatically recognize which serial port is linked to the
 board. Check it manually, and create a file named `mbedls.json` containing
 (at the same level than where you execute all commands):
+
 ```bash
 {
     "50040200074D652F3828F333": {
         "serial_port": "/dev/ttyUSB0"
     }
 }
 ```
+
 Replace `/dev/ttyUSB0` with your correct serial port
 (something like `COM6` on Windows).
 
 * `mbedls` does not link CM3DS target ID with its name, so execute the command:
+
 ```bash
 mbedls --mock 5004:ARM_CM3DS_MPS2
 ```
 
-* You can now compile and run the tests
+* You can now compile and run the tests:
+
 ```bash
 mbed test -m ARM_CM3DS_MPS2 -t COMPILER
 ```
-