Add redirect in Netlify config for moved ARM templates script

[stijnmoreels]

Is your feature request related to a problem? Please describe.
We have chosen to move the ARM and Bicep templates script inside the same category folder, but this means that older links to the ARM feature documentation will break.

Describe the solution you'd like
Add a redirect to the netlify.toml that moves /features/powershell/arm to /features/powershell/templates/arm.

Additional context
Note that this redirect should only be added when the v0.8 feature documentation is published.