fix: fix global tags and updated documentation

[jasperpostcn]

Description

• Added possibility for generic tags for all resources created in the vwan module
• Updated README with new azurerm version

PR Checklist

• I have checked if my changes close any open issues. If so please include appropriate closing keywords below.
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

Changes to existing Resource / Data Source

• I have added an explanation of what my changes do and why I'd like you to include them (This may be covered by linking to an issue above, but may benefit from additional explanation).
• I have made corresponding changes to the documentation
• I have successfully run tests with my changes locally. If not, please provide details on testing challenges that prevented you running the tests.
• (For changes that include a state migration only). I have manually tested the migration path between relevant versions of the provider.

Change Log

• Added possibility for generic tags for all resources created in the vwan module
• Updated README with new azurerm version

This is a (please select all that apply):

• Bug Fix
• New Feature (ie adding a service, resource, or data source)
• Enhancement
• Breaking change (not backwards compatible with previous releases)

[dkooll]

lgtm