DOCS: Clarify Windows use of --creds filename (#2812)

documentation/creds-json.md

@@ -178,9 +178,8 @@ The `--creds` flag allows you to specify a different file name.
 * Do not end the filename with `.yaml` or `.yml` as some day we hope to support YAML.
 * Rather than specifying a file, you can specify a program or shell command to be run. The output of the program/command must be valid JSON and will be read the same way.
   * If the name begins with `!`, the remainder of the name is taken to be a shell command or program to be run.
-  * If the name is a file that is executable (chmod `+x` bit), it is taken as the command to be run.
+  * If the name is a file that is executable (chmod `+x` bit), it is taken as the command to be run (Linux/MacOS only).
   * Exceptions: The `x` bit is not checked if the filename ends with `.yaml`, `.yml` or `.json`.
-  * Windows: Executing an external script isn't supported. There's no code that prevents it from trying, but it isn't supported.
 
 ### Example commands
 
@@ -198,7 +197,7 @@ dnscontrol preview --creds /some/absolute/path/creds.sh
 Following commands would execute a shell command:
 
 ```shell
-dnscontrol preview --creds "!op inject -i creds.json.tpl"
+dnscontrol preview --creds '!op inject -i creds.json.tpl'
 ```
 
 This example requires the [1Password command-line tool](https://developer.1password.com/docs/cli/)