Improve documentation around powerplatform_environment_application_package_install (resource)

[webstean]

Description

Apparently, this resource is intended to be used for install of "Dynamics 365 Apps" which are separate from solutions. These "apps" can be inbuilt or available from Microsoft AppSource. Currently does not mention AppSource, so we need to know how to install "Dynamics 365 Apps" from AppSource. The supplied example is also not very clear on how to leverage this resource.

There also may be dependency on the "Enable Dynamics 365 apps" option being set when the environment is first created.

Definition of Done

• [X ] Users should be able to use the documentation to complete a task

Contributions

Do you plan to raise a PR to address this issue? NO

See the contributing guide for more information about what's expected for contributions.

[webstean]

For example, I would expect this to work:

resource "powerplatform_environment_application_package_install" "install_sample_application" {
  for_each = { for k, v in powerplatform_environment.environments : k => v if k == "coe" }

  environment_id = each.value.id
  unique_name    = "Creator Kit"
}

but it doesn't and errors with:

╷
│ Error: Client error when creating powerplatform
│ 
│   with powerplatform_environment_application_package_install.install_sample_application["coe"],
│   on powerapps-solutions-coe.tf line 275, in resource "powerplatform_environment_application_package_install" "install_sample_application":
│  275: resource "powerplatform_environment_application_package_install" "install_sample_application" {
│ 
│ status: 400, message: {"StatusCode":400,"Message":"Package requested for
│ installation was not found"}
╵