docs(function): add http_option field (#2946)

Author: Codelax

docs/resources/function.md

@@ -87,6 +87,8 @@ The following arguments are supported:
 
 - `deploy` - Define whether the function should be deployed. Terraform will wait for the function to be deployed. Your function will be redeployed if you update the source zip file.
 
+- `http_option` - (Optional) Allows both HTTP and HTTPS (`enabled`) or redirect HTTP to HTTPS (`redirected`). Defaults to `enabled`.
+
 - `sandbox` - (Optional) Execution environment of the function.
 
 - `region` - (Defaults to [provider](../index.md#region) `region`). The [region](../guides/regions_and_zones.md#regions) in which the namespace should be created.