Move schemamd and functionmd packages to internal (#354)

* Move `schemamd` and `functionmd` packages to `internal`

* Add changelog entries

* Switch changelog entry kind to `Breaking Changes`

Author: SBGoods

.changes/unreleased/BREAKING CHANGES-20240410-161445.yaml

@@ -0,0 +1,6 @@
+kind: BREAKING CHANGES
+body: 'schemamd: The `schemamd` package has moved to `internal/schemamd` and can no
+  longer be imported'
+time: 2024-04-10T16:14:45.685307-04:00
+custom:
+  Issue: "354"

.changes/unreleased/BREAKING CHANGES-20240410-161540.yaml

@@ -0,0 +1,6 @@
+kind: BREAKING CHANGES
+body: 'functionmd: The `functionmd` package has moved to `internal/functionmd` and
+  can no longer be imported'
+time: 2024-04-10T16:15:40.388578-04:00
+custom:
+  Issue: "354"

functionmd/render.go renamed to internal/functionmd/render.go

@@ -10,7 +10,7 @@ import (
 
 	tfjson "github.com/hashicorp/terraform-json"
 
-	"github.com/hashicorp/terraform-plugin-docs/schemamd"
+	"github.com/hashicorp/terraform-plugin-docs/internal/schemamd"
 )
 
 // RenderArguments returns a Markdown formatted string of the function arguments.

functionmd/render_test.go renamed to internal/functionmd/render_test.go

@@ -12,7 +12,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	tfjson "github.com/hashicorp/terraform-json"
 
-	"github.com/hashicorp/terraform-plugin-docs/functionmd"
+	"github.com/hashicorp/terraform-plugin-docs/internal/functionmd"
 )
 
 func TestRenderArguments(t *testing.T) {

functionmd/testdata/example_arguments.md renamed to internal/functionmd/testdata/example_arguments.md

@@ -16,10 +16,11 @@ import (
 
 	tfjson "github.com/hashicorp/terraform-json"
 
-	"github.com/hashicorp/terraform-plugin-docs/functionmd"
+	"github.com/hashicorp/terraform-plugin-docs/internal/schemamd"
+
+	"github.com/hashicorp/terraform-plugin-docs/internal/functionmd"
 	"github.com/hashicorp/terraform-plugin-docs/internal/mdplain"
 	"github.com/hashicorp/terraform-plugin-docs/internal/tmplfuncs"
-	"github.com/hashicorp/terraform-plugin-docs/schemamd"
 )
 
 const (