docs: notes for archive_file resource versus data source

docs/data-sources/file.md

@@ -2,12 +2,12 @@
 page_title: "archive_file Data Source - terraform-provider-archive"
 subcategory: ""
 description: |-
-  Generates an archive from content, a file, or directory of files.
+  Generates an archive from content, a file, or directory of files. The archive is built during the terraform plan, so you must persist the archive through to the terraform apply. See the archive_file resource for an alternative if you cannot persist the file, such as in a multi-phase CI or build server context.
 ---
 
 # archive_file (Data Source)
 
-Generates an archive from content, a file, or directory of files.
+Generates an archive from content, a file, or directory of files. The archive is built during the terraform plan, so you must persist the archive through to the terraform apply. See the `archive_file` resource for an alternative if you cannot persist the file, such as in a multi-phase CI or build server context.
 
 ## Example Usage
 

internal/provider/data_source_archive_file.go

@@ -46,7 +46,10 @@ func (d *archiveFileDataSource) ConfigValidators(context.Context) []datasource.C
 
 func (d *archiveFileDataSource) Schema(ctx context.Context, req datasource.SchemaRequest, resp *datasource.SchemaResponse) {
 	resp.Schema = schema.Schema{
-		Description: "Generates an archive from content, a file, or directory of files.",
+		Description: "Generates an archive from content, a file, or directory of files. " +
+			"The archive is built during the terraform plan, so you must persist the archive through to the terraform apply. " +
+			"See the `archive_file` resource for an alternative if you cannot persist the file, " +
+			"such as in a multi-phase CI or build server context.",
 		Blocks: map[string]schema.Block{
 			"source": schema.SetNestedBlock{
 				Description: "Specifies attributes of a single source file to include into the archive. " +