docs: update licensing steps in faq (#16484)

<details>

<summary>this would be a good candidate for an expand
component</summary>

but I don't think they work in our docs yet

</details>


[preview](https://coder.com/docs/@licensing-faq/tutorials/faqs#how-do-i-add-a-premium-trial-license)

---------

Co-authored-by: EdwardAngert <17991901+EdwardAngert@users.noreply.github.com>

docs/admin/licensing/index.md

@@ -47,9 +47,17 @@ There are two ways to add a license to a Coder deployment:
 
 1. Run `coder licenses add`:
 
-   ```shell
-   coder licenses add -f <path to your license key>
-   ```
+   - For a `.jwt` license file:
+
+     ```shell
+     coder licenses add -f <path to your license key>
+     ```
+
+   - For a text string:
+
+     ```sh
+     coder licenses add -l 1f5...765
+     ```
 
 </div>