Add documentation for resourceDerivedTypes experimental feature (#1…

…3163)

Added documentation for the "resource derived types" experimental
feature that was added by #12591

docs/experimental-features.md

@@ -32,6 +32,9 @@ Allows you to define your own custom functions. See [User-defined functions in B
 ### `optionalModuleNames`
 Enabling this feature makes the `name` property in the body of `module` declarations optional. When a `module` omits the `name` property with the feature enabled, the Bicep compiler will automatically generate an expression for the name of the resulting nested deployment in the JSON. If you specify the `name` property, the compiler will use the specified expression in the resulting JSON. For more information, see [Added optional module names as an experimental feature](https://github.com/Azure/bicep/pull/12600).
 
+### `resourceDerivedTypes`
+If enabled, templates can reuse resource types wherever a type is expected. For example, to declare a parameter `foo` that should be usable as the name of an Azure Storage account, the following syntax would be used: `param foo resouce<'Microsoft.Storage/storageAccounts@2022-09-01'>.name`. **NB:** Because resource types may be inaccurate in some cases, no constraints other than the ARM type primitive will be enforced on resource derived types within the ARM deployment engine. Resource-derived types will be checked by Bicep at compile time, but violations will be emitted as warnings rather than errors.
+
 ## Other experimental functionality
 
 ### `publish-provider` CLI Command