🌐 Add section on how the `/readMetadata` CosmosDb NoSql authorization needs to be added for the test fixtures to be used

[stijnmoreels]

Is your feature request related to a problem? Please describe.
When using the NoSql test components, the test client needs to have the /readMetadata permission for it to work in normal circumstances.

Describe the solution you'd like
Currently, there is no mention of this in the docs.

[ClementVaillantCodit]

Here's the Azure CLI command to create the sql role-assignment:

az cosmosdb sql role assignment create
--account-name "CosmosDBAccountName"
--resource-group "ResourceGroupName"
--role-definition-name "Cosmos DB Built-in Data Contributor"
--scope "/"
--principal-id "UserOrPrincipalObjectId"

Reference Data Plane roles
Create Role Assignment