[Documentation] Clarify how {IME:SWITCH:<ime>} works

[user202729]

I figured out that it uses the new input method ID, but for a typical user it would be nontrivial to figure out what it is and how to determine the ID.

(I used Automate for that)

[nimble0]

I don't even remember how I found out an ID to test that command but I know it wasn't easy. If you have a simple method, maybe you could add it to this page: https://github.com/nimble0/dotterel/wiki/Dotterel-commands

[user202729]

You're not allowing people other than you to edit the wiki...

---

This is a detailed instruction (although most users should be able to figure out what to do next after knowing what application to install)

1. Install the application Automate.

   This application is capable of doing many things other than determining input method ID.

2. Create a new flow, and edit it.

3. Create an "Input method set" block, and tap at the block to edit it.

4. Tap the "Pick input method & subtype" button.

5. Choose an input method.

6. Click at the "fx" button at the right side of the "Input method" dialog, and copy the content (exclude the double quotes)

[nimble0]

Ah okay, you should be able to edit it now. I've added those instructions as well.