Fixes hashicorp#30072 - Update documentation to show that the old DIR…

… option can target a single file instead

internal/command/fmt.go

@@ -528,15 +528,16 @@ func (c *FmtCommand) trimNewlines(tokens hclwrite.Tokens) hclwrite.Tokens {
 
 func (c *FmtCommand) Help() string {
 	helpText := `
-Usage: terraform [global options] fmt [options] [DIR]
+Usage: terraform [global options] fmt [options] [TARGET]
 
 	Rewrites all Terraform configuration files to a canonical format. Both
 	configuration files (.tf) and variables files (.tfvars) are updated.
 	JSON files (.tf.json or .tfvars.json) are not modified.
 
-	If DIR is not specified then the current working directory will be used.
-	If DIR is "-" then content will be read from STDIN. The given content must
-	be in the Terraform language native syntax; JSON is not supported.
+	If TARGET is not specified then the current working directory will be
+	used. If TARGET is a file, only that file will be used. If TARGET is
+	"-" then content will be read from STDIN. The given content must be in
+	the Terraform language native syntax; JSON is not supported.
 
 Options:
 

website/docs/cli/commands/fmt.mdx

@@ -45,12 +45,13 @@ and the generated files.
 
 ## Usage
 
-Usage: `terraform fmt [options] [DIR]`
+Usage: `terraform fmt [options] [TARGET]`
 
 By default, `fmt` scans the current directory for configuration files. If
-the `dir` argument is provided then it will scan that given directory
-instead. If `dir` is a single dash (`-`) then `fmt` will read from standard
-input (STDIN).
+a directory is provided for the `target` argument then it will scan that
+given directory instead. If `target` is a file then `fmt` will process just
+that file, and if a single dash (`-`) then `fmt` will read from standard input
+(STDIN).
 
 The command-line flags are all optional. The list of available flags are: