[Modules] Downgrade RBAC API version

[eriqua]

Description

Downgrade roleAssignment Api version from 2021-04-01-preview to 2020-10-01-preview.

Reasons:

• 2020-10-01-preview is the latest documented in the Azure Resource Reference (ARR). Module readmes are linking ARR docs to the api version used and this is currently providing documentation to a different version than the one deployed.
• 2020-10-01-preview fixes the warning on the roleAssignment Warning BCP081: Resource type "Microsoft.Authorization/roleAssignments@2021-04-01-preview" does not have types available.

Pipeline references

For module/pipeline changes, please create and attach the status badge of your successful run.

Pipeline

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update (Wiki)

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (readme)
• I did format my code

[ahmadabdalla]

@eriqua since its updating the docos as well, linter detected some language expression recommendations. Do you wanna update those as well?