Fix azure table storage name length requirement.

https://docs.microsoft.com/en-us/rest/api/storageservices/Understanding-the-Table-Service-Data-Model?redirectedfrom=MSDN#table-names.

azurerm/resource_arm_storage_table.go

@@ -43,9 +43,9 @@ func validateArmStorageTableName(v interface{}, k string) (ws []string, errors [
 			"Table Storage %q cannot use the word `table`: %q",
 			k, value))
 	}
-	if !regexp.MustCompile(`^[A-Za-z][A-Za-z0-9]{6,63}$`).MatchString(value) {
+	if !regexp.MustCompile(`^[A-Za-z][A-Za-z0-9]{3,63}$`).MatchString(value) {
 		errors = append(errors, fmt.Errorf(
-			"Table Storage %q cannot begin with a numeric character, only alphanumeric characters are allowed and must be between 6 and 63 characters long: %q",
+			"Table Storage %q cannot begin with a numeric character, only alphanumeric characters are allowed and must be between 3 and 63 characters long: %q",
 			k, value))
 	}