docs: Remove technical preview verbiage from provider-defined functions

Reference: #966

Author: bflad

Diff for: .changes/unreleased/NOTES-20240329-133959.yaml

@@ -0,0 +1,6 @@
+kind: NOTES
+body: 'function: Provider-defined function features are now considered generally available
+  and protected by compatibility promises'
+time: 2024-03-29T13:39:59.085147-04:00
+custom:
+  Issue: "966"

Diff for: function/definition.go

@@ -12,9 +12,6 @@ import (
 )
 
 // Definition is a function definition. Always set at least the Result field.
-//
-// NOTE: Provider-defined function support is in technical preview and offered
-// without compatibility promises until Terraform 1.8 is generally available.
 type Definition struct {
 	// Parameters is the ordered list of function parameters and their
 	// associated data types.

Diff for: function/function.go

@@ -10,8 +10,7 @@ import (
 // Function represents an instance of a function. This is the core interface
 // that all functions must implement.
 //
-// NOTE: Provider-defined function support is in technical preview and offered
-// without compatibility promises until Terraform 1.8 is generally available.
+// Provider-defined functions are supported in Terraform version 1.8 and later.
 type Function interface {
 	// Metadata should return the name of the function, such as parse_xyz.
 	Metadata(context.Context, MetadataRequest, *MetadataResponse)

Diff for: provider/provider.go

@@ -74,9 +74,6 @@ type ProviderWithConfigValidators interface {
 // include provider defined functions for usage in practitioner configurations.
 //
 // Provider-defined functions are supported in Terraform version 1.8 and later.
-//
-// NOTE: Provider-defined function support is in technical preview and offered
-// without compatibility promises until Terraform 1.8 is generally available.
 type ProviderWithFunctions interface {
 	Provider
 

Diff for: website/docs/plugin/framework/functions/implementation.mdx

@@ -6,13 +6,7 @@ description: >-
 
 # Implement Functions
 
-<Highlight>
-
-Provider-defined function support is in technical preview and offered without compatibility promises until Terraform 1.8 is generally available.
-
-</Highlight>
-
-The framework supports implementing functions based on Terraform's [concepts for provider-defined functions](/terraform/plugin/framework/functions/concepts). It is recommended to understand those concepts before implementing a function since the terminology is used throughout this page and there are details that simplify function handling as compared to other provider concepts.
+The framework supports implementing functions based on Terraform's [concepts for provider-defined functions](/terraform/plugin/framework/functions/concepts). It is recommended to understand those concepts before implementing a function since the terminology is used throughout this page and there are details that simplify function handling as compared to other provider concepts. Provider-defined functions are supported in Terraform 1.8 and later.
 
 The main code components of a function implementation are:
 

Diff for: website/docs/plugin/framework/functions/index.mdx

@@ -8,12 +8,6 @@ description: >-
 
 # Functions
 
-<Highlight>
-
-Provider-defined function support is in technical preview and offered without compatibility promises until Terraform 1.8 is generally available.
-
-</Highlight>
-
 Functions are an abstraction that allow providers to expose computational logic beyond Terraform's [built-in functions](/terraform/language/functions) and simplify practitioner configurations. Provider-defined functions are supported in Terraform 1.8 and later.
 
 <Note>