Fix directory paths in installation notes

Updated directory paths for Linux and Windows instructions.

Author: felipe-iar

NOTES.md

@@ -12,14 +12,14 @@ The recommended solution is to use `git` for fetching up-to-date CMSIS headers:
 ```
 cd /opt/iar/
 git clone https://github.com/arm-software/cmsis_6
-cd ewarm
+cd ewarm/arm
 ln -s ../../cmsis_6/CMSIS CMSIS
 ```
 * Windows (Administrative Command Prompt):
 ```
 cd /iar/
 git clone https://github.com/arm-software/cmsis_6
 mklink -d ewarm-10.xx.x ewarm
-cd ewarm
+cd ewarm/arm
 mklink -d ../../cmsis_6/CMSIS CMSIS
 ```