Update include-directory-stub inline help (#2488)

Update include-directory-stub inline help to match public docs

cmd/copy.go

@@ -2089,7 +2089,7 @@ func init() {
 	cpCmd.PersistentFlags().StringVar(&raw.listOfVersionIDs, "list-of-versions", "", "Specifies a file where each version id is listed on a separate line. Ensure that the source must point to a single blob and all the version ids specified in the file using this flag must belong to the source blob only. AzCopy will download the specified versions in the destination folder provided.")
 	cpCmd.PersistentFlags().StringVar(&raw.blobTags, "blob-tags", "", "Set tags on blobs to categorize data in your storage account")
 	cpCmd.PersistentFlags().BoolVar(&raw.s2sPreserveBlobTags, "s2s-preserve-blob-tags", false, "Preserve index tags during service to service transfer from one blob storage to another")
-	cpCmd.PersistentFlags().BoolVar(&raw.includeDirectoryStubs, "include-directory-stub", false, "False by default to ignore directory stubs. Directory stubs are blobs with metadata 'hdi_isfolder:true'. Setting value to true will preserve directory stubs during transfers.")
+	cpCmd.PersistentFlags().BoolVar(&raw.includeDirectoryStubs, "include-directory-stub", false, "False by default to ignore directory stubs. Directory stubs are blobs with metadata 'hdi_isfolder:true'. Setting value to true will preserve directory stubs during transfers. Including this flag with no value defaults to true (e.g, azcopy copy --include-directory-stub is the same as azcopy copy --include-directory-stub=true).")
 	cpCmd.PersistentFlags().BoolVar(&raw.disableAutoDecoding, "disable-auto-decoding", false, "False by default to enable automatic decoding of illegal chars on Windows. Can be set to true to disable automatic decoding.")
 	cpCmd.PersistentFlags().BoolVar(&raw.dryrun, "dry-run", false, "Prints the file paths that would be copied by this command. This flag does not copy the actual files. The --overwrite flag has no effect. If you set the --overwrite flag to false, files in the source directory are listed even if those files exist in the destination directory")
 	// s2sGetPropertiesInBackend is an optional flag for controlling whether S3 object's or Azure file's full properties are get during enumerating in frontend or