[DOCS] Document the difference between `ultrathink` and Thinking Mode On/Off

Documentation Type

Missing documentation (feature not documented)

Section/Topic

Thinking Mode

What's Wrong or Missing?

In Claude Code v1, there used to be three different thinking levels:

• think
• think hard (more thinking)
• ultrathink (even more thinking)

Now, in Claude Code V2, you deprecated these thinking levels, and introduced a new "Thinking On/Off" mode that is toggleable by pressing TAB.

I noticed you removed the color highlighting for think and think hard, but they kept ultrathink.

Suggested Improvement

The question is - how does Thinking On/Off relate to ultrathink? Do they complement each other?

Impact

Medium - Makes feature difficult to understand