Edit addition to tools_intro.md

Edit note, mostly for branding and brevity.

Author: Amanda Butler

docs/tools/tools_intro.md

@@ -27,7 +27,7 @@ Mbed OS 5 can be built with various toolchains. The currently supported versions
 
 ##### Arm Mbed Online Compiler
 
-The Mbed Online Compiler is our in-house IDE and should be familiar to anyone who's been working with Mbed for a while. It switches the backing toolchain based on the architecture version as in the table below.
+The Mbed Online Compiler is our in-house IDE and should be familiar to anyone who's been working with Mbed for a while. It switches the backing toolchain based on the architecture version:
 
 | Architecture version | Compiler |
 |----                  |----           |
@@ -38,7 +38,7 @@ The Mbed Online Compiler is our in-house IDE and should be familiar to anyone wh
 
 For more information, please see the [Online Compiler page](developing-mbed-online-compiler.html).
 
-<span class="note"> **Note:** With Mbed-OS 5.12 release, ARM Compiler 6 will be the default ARM toolchain for Mbed-OS developmet. Majority of Mbed OS targets/platforms are already compatible with ARM Compiler 6. Some existing targets still using/supporting ARM Compiler 5 will also be migrated to ARM Compiler 6 in future. Please be aware that all new/existing Mbed OS targets/developers must use ARM Compiler 6 for future development and all code contributions to Mbed OS will be validated with ARM Compiler 6. </span>
+<span class="note"> **Note:** Arm Compiler 6 is the default ARM toolchain for Mbed OS developmet. Most Mbed OS platforms are already compatible with Arm Compiler 6. Some existing targets still supporting Arm Compiler 5 will also be migrated to ARM Compiler 6 in the future. Please be aware that you must use Arm Compiler 6 for future development, and we will validate all code contributions to Mbed OS with Arm Compiler 6. </span>
 
 ##### Third party development tools